Neuroscience Teachers Guide

The

BRAINin Space

A Teacher’s Guide With Activities for Neuroscience

Educational Product

Teachers Grades 5Ð12National Aeronautics andSpace Administration

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The Brain in SpaceA Teacher’s Guide With Activities for Neuroscience

National Aeronautics and Space Administration

Life Sciences DivisionWashington, DC

This publication is in the Public Domain and is not protected by copyright.Permission is not required for duplication.

EG-1998-03-118-HQ

Acknowledgments This publication was made possible by the NationalAeronautics and Space Administration, CooperativeAgreement No. NCC 2-936.

Principal Investigator:

Walter W. Sullivan, Jr., Ph.D.Neurolab Education ProgramOffice of Operations and PlanningMorehouse School of MedicineAtlanta, GA

Writers:

Marlene Y. MacLeish, Ed.D.Director, Neurolab Education ProgramMorehouse School of MedicineAtlanta, GA

Bernice R. McLean, M.Ed.Deputy Director, Neurolab Education ProgramMorehouse School of MedicineAtlanta, GA

Graphic Designer and Illustrator:

Denise M.Trahan, B.A.Atlanta, GA

Technical Director:

Perry D. RigginsNeurolab Education ProgramMorehouse School of MedicineAtlanta, GA

The Brain in Space: A Teacher’s Guide with Activities for Neuroscience,EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12 7

Contributors

This publication was developed for the National Aeronautics and Space Administration (NASA)under a Cooperative Agreement with the Morehouse School of Medicine (MSM). Many individu-als and organizations contributed to the production of this curriculum. We acknowledge theirsupport and contributions.

Organizations:Atlanta Public School SystemSociety for NeuroscienceThe Dana Alliance for Brain Initiatives

NASA Headquarters:Code UL, Life Sciences DivisionMary Anne Frey, Ph.D.Rosalind A. Grymes, Ph.D.David R. Liskowsky, Ph.D.

Code FE, Education DivisionPamela L. Mountjoy

Education Program ManagerNASA HeadquartersWashington, DC

Jane A. GeorgeEducational Materials SpecialistTeaching From Space ProgramWashington, DC

Gloria BarnesPublications Manager

Karol Yeatts, Ed.D.

NASA-Ames Research CenterJoseph Bielitzki, D.V.S., M.S.

Morehouse School of Medicine Neuroscience Institute:

Peter MacLeish, Ph.D.John Patrickson, Ph.D.Holly Soares, Ph.D.

Joseph Whittaker, Ph.D.Neurolab Education Program Advisory Board:Gene BrandtMilton C. Clipper, Jr.Mary Anne Frey, Ph.D.Charles A. Fuller, Ph.D.Rosalind A. Grymes, Ph.D.William J. Heetderks, M.D., Ph.D.Peter R. MacLeish, Ph.D.Charles M. Oman, Ph.D.Rhea Seddon, M.D.Jane Smith, Ed.D.Ronald J. White, Ph.D.

Consulting Editors:Ron Booth, Ph.D.James Denk, M.A.Wyckliffe Hoffler, Ph.D.Roy Hunter, Ph.D.Fernan Jaramillo, Ph.D.Ollie Manley, Ph.D.Nancy Pearson Moreno, Ph.D.Barbara Tharp, M.S.Gregory L.Vogt, Ed.D.

Lesson/Activity Contributors:Timothy Aman, M.S.Kenneth M. Baldwin, Ph.D.Luis Benavides, Ph.D.Gunnar C. Blomqvist, M.D., Ph.D.Bernard Cohen, M.D.Charles A. Czeisler, Ph.D., M.D.

8The Brain in Space: A Teacher’s Guide with Activities for Neuroscience,

EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12

Lesson/Activity Contributors (Continued):Dwain L. Eckberg, M.D.Charles A. Fuller, Ph.D.Kathleen Heffernan, Ph.D.Stephen M. Highstein, M.D., Ph.D.Gay Robbins Holstein, Ph.D.Jerry L. Homick, Ph.D.Eberhard R. Horn, Ph.D.Kenneth S. Kosik, M.D.Bruce L. McNaughton, Ph.D.Richard S. Nowakowski, Ph.D.Gina Poe, Ph.D.Gordon Kim Prisk, Ph.D.Danny Riley, Ph.D.Muriel D. Ross, Ph.D.Janet Silvera, B.Sc.Dan Sulica, M.Sc.Kerry D. Walton, Ph.D.Bonita Waters-Alick, Ph.D.John B. West, M.D., Ph.D., D.Sc.Michael L. Wiederhold, Ph.D.

The Brain in Space: A Teacher’s Guide with Activities for Neuroscience,EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12 i

Recommended Guide Usage

The lessons and activities in this guide willengage your students in the excitement ofspace life science investigations after theNeurolab Spacelab mission. It is our goal thatthe information in this guide will inspire bothyou and your students to become interestedand active participants in this space mission.Few experiences can compare with the excite-ment and thrill of watching a Shuttle launch.This guide provides an opportunity for you andyour students to go one step further by con-ducting the experiments on Earth that are rele-vant to the research conducted in space.

The Brain in Space teacher’s guide is written foryou, the teacher. The activities presented in TheBrain in Space are most appropriate for middleand high school life sciences teachers and theirstudents. The NASA Neurolab Space Shuttleflight, STS 90, was scheduled for lift-off inApril 1998.

National Science and Math Education StandardsThe Brain in Space activities are compatiblewith the National Science and Math EducationStandards. Because many of the activities anddemonstrations apply to more than one subjectarea, a matrix chart relates activities to nationalstandards in science and mathematics and toscience process skills. In each matrix, the sci-ence and math content standards are listedalong the left margin. Activities within a givensection that fulfill a listed standard or includethe development of a listed skill are designatedwith the symbol “•” in the appropriate column.

Scientific MethodSince scientists’ jobs frequently call for effectivecommunication of scientific results to the com-munity, special emphasis is placed on involvingstudents in activities that require the develop-ment and delivery of scientific presentations.Appropriate scientific processes are modeledthroughout The Brain in Space guide to assiststudents in acquiring basic investigative skills.

Using The Brain in Space ActivitiesThe Brain in Space activities focus on specificeffects of weightlessness and other aspects ofthe space environment on:

• developmental and cellular neurobiology,• vestibular function,• spatial orientation and visuo-motor

performance,• autonomic nervous system regulation, and• sleep and circadian rhythms.

Before beginning any hands-on activities withyour students, you may want to learn moreabout the nervous system and how it is affectedby the microgravity environment. This infor-mation is covered in the following introductorysections: “The Space Life Sciences” (page 3),“Space Neuroscience” (page 5), and “TheNervous System” (page 13). Additional infor-mation is provided for you in the “Things toKnow” and “Background” sections in Part II.

This guide begins with an overview ofNeurolab and background information onspace life sciences, space neuroscience, and

iiThe Brain in Space: A Teacher’s Guide with Activities for Neuroscience,


space life sciences research. The sections onspace life sciences focus on changes in organ-isms under conditions of microgravity, whetheror not organisms can withstand these changes,finding ways to make space flight safer, andapplying space technologies to solve scientificand medical problems on Earth.

Following Part I are lessons and activities thatdemonstrate and/or examine the effect ofweightlessness and other aspects of the spaceenvironment on the nervous system. The manyactivities contained in this guide emphasizehands-on/minds-on involvement, prediction,data collection and interpretation, teamwork,and problem-solving. Most of the activities uti-lize basic and inexpensive materials. In eachactivity, you will find diagrams, material lists,and instructions. A brief science backgroundsection within each activity amplifies the con-cepts covered.

The length of time required for each activityvaries according to its degree of difficulty andthe developmental level of the students. Manyof the activities can be completed in a singleclass period. Others require several periods forthe completion of an investigation.

The guide concludes with a glossary of terms,NASA educational resources, and a printed“Teacher Reply Card.” We would appreciateyour assistance by completing and mailing inthe Teacher Reply Card at the end of this guide.

The Brain in Space: A Teacher’s Guide with Activities for Neuroscience,EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12 iii

Objects have observable properties • • • • •Substances react chemically • •Chemical elements •Describing and measuring motion of an object •Forces and movement of objects •Energy (heat, light, electricity,

motion, sound, etc.)Heat transferLight (transmission, absorption, scattering) •Electrical circuits •Sun as source of energy on Earth

Organization of living systems • • • • •All organisms are composed of cells • • • • •Functions of cells necessary for life • • • • •Specialization of functions • • • • •

(cells, tissues and organs)Basic human body systems • • • • •Disease • • • • •Reproduction (asexual and sexual)Heredity, learning and characteristics

of organismsResources needed by organisms • •Regulation of the internal environment • • •Behavior • • • •Populations and ecosystems

Structure of the EarthEarth forces • • •SoilWaterAtmosphere and weatherEarth history and the fossil recordEarth in the solar systemMovement and gravity • • •

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National Science Education StandardsGrades 5–8 Content Standards

Correlation of Science Themes and Activities in The Brain in Space:Activities for Neuroscience

PHYSICAL SCIENCE

LIFE SCIENCE

EARTH SCIENCE

ivThe Brain in Space: A Teacher’s Guide with Activities for Neuroscience,


Methods of science and technology • • • • •Different contributions by people • • • • •

to science and technologyTrade-offs and unintended consequences • • • • •

in technological designs

Personal health (exercise, safety, nutrition, • • • • •tobacco, alcohol)

Environmental health • • • • •Degradation of environmentsNatural and human-induced hazardsRisk analysisInfluence of science and technology on society • • • • •Scientists and engineers work in many settings • • • • •Ethical codes governing research • • • • •

with human subjectsLimitations of science and technology

to solving problems

Contributions of men and women to science • • • • •Science requires different abilities • • • • •Nature of science (method, research, • • • • •

evaluation)History of science • • • • •

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National Science Education StandardsGrades 5–8 Content Standards (Continued)

SCIENCE INPERSONAL AND SOCIALPERSPECTIVES

SCIENCE ANDTECHNOLOGY

HISTORY ANDNATURE OF SCIENCE

The Brain in Space: A Teacher’s Guide with Activities for Neuroscience,EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12 v

Structure of atoms • •Structure and properties of matter •

(elements, chemical bonds)Properties of carbon-containing compounds • • •Chemical reactions (energy, electron transfer, • • •

role in living systems)Motion and forces (gravitation, electric forces, • • •

charges, magnetism)Conservation of energy and entropy •Interactions of energy and matter (waves, • • •

electromagnetic waves, conductance)

Cells (structure, chemical, functions, • • • • •differentiation)

Molecular basis of heredity •Biological evolution •Interdependence of organisms (energy flow • • • • •

in ecosystems, populations)Matter, energy and organization in living systems • • • • •Behavior of organisms • • • • •

(nervous system, role of stimuli)

Energy in the Earth system (role of sun, energy •transfer, global climate)

Geochemical cyclesOrigin and evolution of the Earth systemOrigin and evolution of the universe

Aspects and abilities related to • • • • •technological design

Scientists in different disciplines • • • • •use different methods

Role of new technologies in advancing science • • • • •Purposes of science and technology • • • • •

National Science Education StandardsGrades 9–12 Content Standards

Correlation of Science Themes and Activities in The Brain in Space:Activities for Neuroscience Dev

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PHYSICAL SCIENCE

LIFE SCIENCE

EARTH SCIENCE

SCIENCE ANDTECHNOLOGY

viThe Brain in Space: A Teacher’s Guide with Activities for Neuroscience,


Role of personal and community decisions • • • • •in health (nutrition, disease, accidents)

Population growth and carrying capacityNatural resources (use and limitations)Environmental quality •Natural and human-induced hazardsRole of science and technology in solving • • • • •

local, national and global problems

Contributions of individuals and teams • • • • •to science

Ethics in science • • • • •Nature of scientific knowledge • • • • •History of science (cultural perspectives, • • • • •

how science advances)

National Science Education StandardsGrades 9–12 Content Standards (Continued)

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SCIENCE IN PERSONAL AND SOCIAL PERSPECTIVES

HISTORYAND NATUREOF SCIENCE

The Brain in Space: A Teacher’s Guide with Activities for Neuroscience,EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12 vii

Problem solving • • • • •Communication • • • • •Reasoning • • • • •Connections • • • • •Number relationships • • •Computation and estimation • • • •Patterns and functions • • •AlgebraStatistics • •ProbabilityGeometry • • • •Measurement • • • • •

Grades 9–12

Problem solving • • • • •Communication • • • • •Reasoning • • • • •Connections • • • • •AlgebraFunctions • •Synthetic perspectiveAlgebraic perspectiveTrigonometryStatistics • •ProbabilityDiscrete mathematicsUnderpinnings of calculusMathematical structure

National Council of Teachers of Mathematics Curriculum andEvaluation StandardsGrades 5–8

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The Brain in Space: A Teacher’s Guide with Activities for Neuroscience,EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12 ix

Table ofContents

Part INational Science Education Standards Review

National Council of Teachers of MathematicsCurriculum and Evaluation Standards Review

Introduction...........................................................................................1

Overview: Neurolab and The Brain in Space ..................................2

The Space Life Sciences .....................................................................3

Space Neuroscience:A Special Area Within the Space Life Sciences.................................5

Space Life Sciences Research.............................................................6

Neurolab:A Special Space Mission to Study the Nervous System..................10

The Nervous System .........................................................................13

Part IINeurolab Lessons & Activities..............................................................21

The Scientific Method.......................................................................22Activity I: Introduction to the Scientific Method.........................26

Section I: Developmental and Cellular Neurobiology.....................33

Activity I: What Cells Can I See in Muscle and Spinal Cord Tissue?. .............................................37

Activity II: Target Recognition and Synapse Formation During Development...........................................44

Activity III: Motor Skills Development............................................47

Section II: Vestibular Function............................................................55

Activity I: Visualizing How the Vestibular System Works............59Activity II: Vestibular-Ocular Reflex...............................................66

xThe Brain in Space: A Teacher’s Guide with Activities for Neuroscience,


Table ofContents

Section III: Spatial Orientation and Visuo-motor Performance ............................................75

Activity I: Finding Your Way Around Without Visual or Sound Cues...............................81

Activity II: Pitch, Roll and Yaw: The Three Axes of Rotation.......87Activity III: Building a Magic Carpet...............................................89Activity IV: Building a 3-D Space Maze: Escher Staircase..............95

Section IV: Autonomic Nervous System Regulation.......................101

Activity I: Measuring Blood Pressure in Space.............................105Activity II: Changing Body Positions:

How Does the Circulatory System Adjust?............117Activity III: Baroreceptor Reflex Role Play......................................123

Section V: Sleep and Circadian Rhythms ..........................................127

Activity I: The Geophysical Light/Dark Cycle .............................131Activity II: How Quick Are Your Responses? ................................134Activity III: Measuring Your Breathing Frequency at Rest.............138Activity IV: How Long Can You Hold Your Breath?.......................142Activity V: Raising the Level of Carbon Dioxide

in Your Blood.................................................................146

Section VI: Appendices.........................................................................149

Glossary ..............................................................................................150NASA Resources for Educators.........................................................159

The Brain in Space: A Teacher’s Guide With Activities for Neuroscience,EG-1998-03-118-HQ, Education Standards, Grades 5–8, 9–12 1

Introduction

Overview: Neurolab and The Brain in Space

The Space Life Sciences

Space Neuroscience

Space Life Sciences Research

Neurolab: A Special Space Mission to Study the Nervous System

The Nervous System

Part I

2The Brain in Space: A Teacher’s Guide With Activities for Neuroscience,


Introduction Overview

In recognition of the tremendous advances thathave been made in neuroscience and the behav-ioral sciences, the President and Congress desig-nated the 1990s as the “Decade of the Brain.”In response, the National Aeronautics and SpaceAdministration (NASA) decided that an impor-tant and significant contribution could be madeto the national research effort through aShuttle/Spacelab mission (Neurolab) dedicatedto research on the nervous system and behavior.

Neurolab was a seventeen-day life sciences SpaceShuttle mission. It carried a payload of 26 neu-roscience experiments in celebration of the“Decade of the Brain.” Five additional “NeurolabProgram” experiments will fly on other mis-sions. Seven astronauts (plus two alternates)were selected to fly aboard the Neurolab mis-sion, STS 90, launched in April of 1998.TheNeurolab science payload examined the effectsof weightlessness and other aspects of the spaceenvironment on the nervous system.TheMorehouse School of Medicine, in collaborationwith NASA, has produced this supplementalinstructional guide to increase secondary teach-ers’ and students’ understanding of the mecha-nisms responsible for neurological and behav-ioral changes in space.

Overview:Neurolab and The Brain in Space


Life evolved on Earth under a unique set ofconditions.These conditions, which make upEarth’s environment, are very different from theenvironment of space. Some of the most notabledifferences between conditions on Earth and inspace are related to gravity, temperature, dailyand seasonal cycles, atmosphere, radiation andmagnetic fields. Systems for human space flightcompensate for many of these differences.Thespace life sciences use space flight as a uniquelaboratory to study the effects of very low levelsof gravity (“weightlessness”) on humans andother biological systems and look for ways tocounteract those effects that can be detrimentalto human space crew members.

Gravity is an invisible attractive force that is basicto all matter. The amount of gravity, or “pull,”exerted by an object depends both on its massand its distance from other objects. Earth’s grav-ity is responsible for keeping inplace the cloud of gases surround-ing the planet, known as the atmos-phere, and for holding objects onthe surface. Even the moon andman-made satellites are kept in theirelliptical orbits around the planet byEarth’s gravitational field.

However, as one moves farther awayfrom the surface, the pull exerted byEarth’s gravity becomes weaker. In atypical Space Shuttle orbit, gravity’spull is about 94 percent the pullexperienced at Earth’s surface.However, astronauts inside theirspacecraft appear to float becausethe Space Shuttle and the astronautsinside are in “free fall.” The orbit

they are traveling in is a curved path that is theresult of the forward motion imparted by rocketengines during launch and the pull of gravity. Byachieving the right forward speed, the shape ofthe Shuttle’s falling path matches the curvature ofEarth. Consequently, the Shuttle remains at anearly constant altitude as it falls. Another way ofstating this is that the gravitational pull of Earth isoffset by a centrifugal force in the opposite direc-tion related to the acceleration of the spacecraft.

A falling elevator car, as shown in Figure 1,is an example of the effect of “free fall.”This condition can be imagined by consid-ering what would happen if the cables on anelevator were to break.The elevator and anypassengers inside would fall toward Earth atthe same rate.

Introduction The Space Life Sciences

The Space Life Sciences

Figure 1 Diagram of free fall.

NormalWeight

Heavier Than Normal

LighterThan Normal

DCBAA. Individual experiences normal

weight.B. Because of the upward accelera-

tion, the individual’s apparent weight increases somewhat.

C. Because of the downward acceler-ation, the individual’s apparent weight decreases somewhat.

D. Because of free fall, no weight ismeasured.

No MeasuredWeight



Introduction The Space Life Sciences

Since gravity is not completely offset at allpoints within the space vehicle, the term“microgravity” is used to describe the condi-tion of near weightlessness in space. Space lifescientists are able to conduct experiments undermicrogravity aboard Space Shuttle missions.Thus, astronauts circling the planet in a space-craft do not feel the effects of gravity.

Space life scientists are interested in learningabout changes in organisms under conditionsof microgravity.These changes take place at thecellular, systemic, and organismal levels.

Studying cellular systems helps scientists tolearn about some of the changes that occurwithin whole biological systems in space. Mostare disrupted in some way when exposed tomicrogravity. Space life scientists hope to under-stand how and why changes in cellular andbody systems take place so that they can under-stand how gravity has influenced evolution,development, and function on Earth. In terms ofhuman space travel, there is also a need todevelop effective “countermeasures,” or treat-ments, to lessen or eliminate the possible detri-mental effects caused by the space environment.

A particular focus of space life sciences researchis seeking answers to questions about changesthat occur in the human body when it islaunched from Earth’s surface, remains in themicrogravity environment of space, and thenreturns to Earth.

Some of the questions that space life scientistsask are:

• How does the human body adjust to micro-gravity? We know, for example, that bodyfluids redistribute within the body in micro-

gravity. What happens to the human heartand blood vessels under these conditions?

• What are some of the changes that takeplace in cells and tissues, and why do thechanges take place? For example, we knowthat muscles lose mass and that bones loseminerals after periods of weightlessness.Space life scientists would like to know whyand how this happens, and whether theseprocesses can be prevented.

• Do cells reproduce and function normallyin microgravity?

• Why do some people have motion sicknessduring the first few days in space?

• How do the timing clocks that set the body’sbiological and physiological rhythms changein microgravity?

As an example of the types of questions exam-ined by space life scientists, consider how thehuman heart adjusts to shifts in the body’s fluidsin microgravity. On Earth, gravity pulls fluidstoward the lower parts of the body (Figure 2A).In microgravity, bodily fluids move from thefeet, legs, and lower trunk toward the upperbody, trunk, and head.This redistribution of flu-ids causes the heart to become temporarilyenlarged because of the increased upper bodyblood volume (Figure 2B).The body reacts toincreased blood volume by eliminating fluids.This elimination decreases the total amount offluid within the cardiovascular system andallows the heart to return to a smaller size(Figure 2C).When astronauts return to Earth,gravity once again pulls body fluids toward thelower parts of the body (Figure 2D).

The amount of fluid within the heart and car-diovascular system is no longer sufficient for


Introduction Space Neuroscience

normal functioning. Not enough oxygen-con-taining blood is pumped to the brain and some-times people returning to Earth tend to faint.

Space life scientists are interested in studyingthese types of changes because it is importantto ensure the health of astronauts in space andfacilitate the quick resumption of their normallives when they return to Earth. Many of thebodily changes that occur in space resemblethose we associate with aging. For example, inspace, humans lose density in their bones andmass in their muscles. They may also suffer lossof balance, dizziness, and disorientation whenthey come back to Earth (Figure 3). Space lifescience research into these conditions has thepotential to provide information that could behelpful to physicians as they cope with prob-lems in people as they age on Earth.

Space Neuroscience: A Special AreaWithin the SpaceLife SciencesSpace life scientists also would like to learnhow space flight and microgravity affect thenervous system.This area of research is knownas space neuroscience.

The study of the ways in which thebody’s brain, spinal cord, and networkof nerves control the activities of ani-mals and humans is called neuroscience.

Figures 2A, 2B, 2C, 2D Diagram of fluid shift. Used by permission (Ronald J.White, 1990)

A B C D

Before

After

Figure 3 Diagram of astronaut showing signs of dizziness and disorientation after space flight.



Space neuroscientists, for example, are interest-ed in understanding how microgravity createsconflicts in the sensory systems of animals.Animals use signals from their sensory systems—vestibular (balance), visual, skin, joint, andmuscle—to maintain a stable vision, spatial ori-entation, eye-head coordination, posture, andlocomotion. In microgravity, the stimuli arechanged. Until they adapt to these changes,humans experience illusory motions in them-selves or in their environments, space motionsickness, difficulty in eye-head-hand coordina-tion, and trouble maintaining balance.Thesedisturbances often reoccur after people returnto Earth.

Space Life SciencesResearchIn the early years of space life sci-ences research, 1948 to 1957, sci-entists wanted to learn whetheranimals could withstand the haz-ards of space flight before theyattempted to send human beingsinto space. The first successfulspace flight with live animals tookplace on September 20, 1951,when the former Soviet Union senta monkey and eleven mice intospace and back in a rocket.(Rockets, unlike spacecraftdesigned for orbital flights, arethrust into the atmosphere andthen drop back to Earth withoutgoing into orbit.) The firstunmanned orbital flight took place

on October 3, 1957, when the former SovietUnion launched Sputnik 1. (Sputnik is aRussian word meaning “satellite.”) It was fol-lowed by Sputnik 2, launched November 3,1957. Sputnik 2 carried a dog named Laikahoused in a pressurized compartment. Laikasurvived for one week only, but the beating ofher monitored heart in space proved that ani-mals could survive the launch. Other studieswith animals in space successfully returnedtheir passengers to Earth.These experiencespaved the way for human space travel by dis-proving prevailing scientific theories that somevital organs might not function in microgravity.

Soviet cosmonaut,Yuri Gagarin, was the firstperson to orbit Earth, which he did on April15, 1961.The first piloted United States flightwas Mercury, Freedom 7, which lifted off on

May 5, 1961, carrying AlanShepard, the first American to flyinto space. Subsequent Mercuryflights proved to medical scientiststhat human beings could fly intospace safely. However, these flightsalso made it clear that the humanbody experiences changes, such asfluid redistribution and weightloss, during space travel.

The United States-sponsoredGemini (Figure 4) missions tookplace during 1965 and 1966. In-flight medical studies revealed thatadditional physiological changes,such as loss of bone density andmuscle mass, occur during spaceflight. Medical scientists concludedthat these changes would not pre-vent human beings from traveling

Introduction Space Life Sciences Research

Figure 4 Photograph of Gemini.



to the Moon, and in May 1961, President JohnF. Kennedy declared that the United States ofAmerica would do just that.

Between 1968 and 1972, 11 manned Apollo(Figure 5) flights were launched, carrying outlunar exploration and demonstrating thathumans can survive and work on the Moon,which has one-sixth the gravity of Earth.Theprogram included 29 astronauts, 12 of whomspent time on the lunar surface. Apollo-eraastronauts reported two major changes in theirbodies during their space travel: motion sicknessand changes in sleep patterns.

The close confines of the early Mercury, Gemini,and Apollo capsules ruled out sophisticatedexperimentation because these spacecrafts weretoo small to accommodate research equipment.It was not until 1973, with the advent of NASA’sSkylab program, which allowed astronauts toremain in space for periods of up to 84 days,that scientists were able to conduct detailedmonitoring of astronauts’ bodies in space.Scientists observed a variety of changes, includ-ing shifts in body fluids, disturbances in the vestibular system, muscle atrophy, loss of red

blood cells, and decreases in bone density. Thescientific data from the three Skylab missionsremain a significant source of descriptive infor-mation for space life scientists for making pre-dictions about human bodily changes in space.

In 1981, the Space Shuttle (Figure 6) was intro-duced.This reusable spacecraft made it possiblefor space life scientists to conduct more elabo-rate experiments in a special laboratory module,called Spacelab, which is housed in the payloadbay of the Space Shuttle.This laboratory is a pres-surized module designed for scientists to con-duct experiments in space. It is made up of twosegments: the core segment, which containscomputers and utilities, and the experiment seg-ment, which contains working laboratory spaceand floor-mounted racks that house specimens,hardware, equipment, and supplies.

Two very important life sciences research pro-grams with origins in the Skylab project wereconducted during Spacelab missions in theShuttle era.The first mission, flown in June1991, provided the first opportunity sinceSkylab to study fully the changes that occur inhuman physiology when the body is in micro-gravity.The second mission, which lasted for 14

Figure 5 Photograph of Apollo.

Figure 6 Photograph of the Space Shuttle.



days, was a continuation of the first mission,and studied cardiovascular, pulmonary, nervous,musculoskeletal, and metabolic systems ofhumans and rodents.

NEUROLAB SPACE AGENCIES

Six space agencies (Figure 7) participatedin Neurolab and otherwise have led theway to greater collaboration in space lifesciences research. They are the UnitedStates National Aeronautics and SpaceAdministration (NASA), the EuropeanSpace Agency (ESA), the Canadian SpaceAgency (CSA), the Centre Nationald’Etudes Spatiales (CNES) of France, theGerman Space Agency—DeutschesZentium fur Luf-Und Raumfahrt (DLR),and the National Space DevelopmentAgency of Japan (NASDA). In June 1995,these agencies developed theInternational Strategic Plan for Space LifeSciences, outlining how the field of spacelife sciences could be best developed fromthe present into the 21st Century.

The National Aeronautics and SpaceAdministration (NASA) of the United StatesNASA was established in 1958, in response tothe Soviet Union’s launching of Sputnik 1. Itsspace life sciences research program seeks tosupport long-term human exploration of spaceand use the unique characteristic of space as aresearch tool to study basic biological processes.

The European Space Agency (ESA)ESA, headquartered in Paris, France, is an inter-national organization comprised of fourteenmember states: Austria, Belgium, Finland,France, Denmark, Germany, Italy, Ireland,TheNetherlands, Norway, Spain, Sweden,Switzerland, and the United Kingdom (Figure8).The Agency was instituted in 1975 with themerger of two organizations that were alreadyinvolved in Europe’s space program since the early 1960s.


Figure 7 Diagram of Neurolab’s six participating space agencies.

Figure 8 Diagram of the ESA member states.


Canadian Space Agency (CSA)CSA was founded in 1989. Canada also partici-pates in the international space program as anassociate member of ESA and as a member ofthe International Space Station Program. CSAheadquarters is located in Ottawa, Canada.TheCanadian space life sciences program has par-ticipated in a series of Spacelab missions withexperiments that examine how humans adaptto space flight.

Centre National d’Etudes Spatiales (CNES) of FranceCNES, created in 1961, has five locations: head-quarters in Paris; rocket activities in Evry; techni-cal activities in Toulouse; launch site in Kourou;and stratosphere balloon activities in Aire surl’Adour.The CNES space life sciences programwas established in 1970 to investigate five areas:neuroscience; cardiovascular science; muscu-loskeletal physiology; gravitational biology; andexobiology.

Deutsches Zentium fur Luf-Und Raumfahrt(DLR) of GermanyThe German life sciences research programbegan in 1972 with experiments on radiationbiology. This program now focuses on theresponses of biological systems to space ele-ments, the exploration ofEarth’s ecosystem, and theacquisition of medical andtechnological knowledge tomaintain human presencein space. DLR’s humanphysiology program focus-es on the cardiovascular,nervous, musculoskeletal,and endocrine systems.

The National Space Development Agency(NASDA) of JapanEstablished in 1969, NASDA oversees develop-ment of, and practical space applications for,Japan. It is responsible for developing andlaunching space vehicles and for overseeingspace experiments and involvement with theInternational Space Station. Japan has a longhistory of collaboration with other space agen-cies, and is developing the Japanese ExperimentModule (JEM) that will be attached to theInternational Space Station.

The Russian Space Agency was not a partner onNeurolab. However, the Russian Space Station,Mir, has provided invaluable opportunities forstudying physiological and psychosocial issuesthat will play a role in the success of future long-duration International Space Station missions.

THE INTERNATIONAL SPACE STATION

At present, each Shuttle mission must take allthat is needed for survival and for conductingscience in space. By constructing a permanentspace station, it becomes possible to assembleequipment and materials for longer-durationexperiments and resupply without disrupting thescientific experiments.The International Space

Station (Figure 9) will allowscientists from around theworld to conduct suchexperiments. Scientists willbe able to leave a criticalamount of equipment onthe Space Station—certainequipment will be “stock-piled” so that the astronautswill not have to return toEarth for material.


Figure 9 Illustration of the International Space Station.



President George Bush and the United StatesCongress declared the 1990s to be the “Decadeof the Brain.”This declaration recognized the spectacular advances that have taken place inneuroscience research over the past twenty-fiveyears and encouraged further research. Aptlycalled “the last frontier of human biology,”neuroscience research holds infinite possibili-ties for greater understanding of how the nervous system works and for preventing and treating nervous system ailments.

In response to the President’s declaration, NASAdedicated a Spacelab Shuttle mission to conductresearch on the nervous system and behavior inspace.This 17-day mission, called Neurolab, wasscheduled for launch in April of 1998. Its mainobjectives were the study of basic neuroscienceresearch questions and the exploration ofmechanisms responsible for neurological andbehavioral changes in space.

In keeping with its history of collaborationwith other space agencies, and in order to takeadvantage of the talents of the neuroscienceresearch community, NASA planned theNeurolab Shuttle mission as a collaborativeeffort among NASA, other national researchagencies, such as the National Institutes ofHealth (NIH): Division of Research Grants,National Institute on Aging, National Institute onDeafness and Other Communication Disorders,National Heart, Lung, and Blood Institute,National Institute on Neurological Disorders andStroke, the National Institute on Child Healthand Human Development, National ScienceFoundation (NSF), the Office of Naval Research(ONR), and international space agencies inter-ested in how microgravity affects the nervoussystem.

Accordingly, in July 1993, NASA issued anAnnouncement of Opportunity, soliciting pro-posals for experiments to be conducted on theNeurolab mission.The announcement was fol-lowed by a series of pre-proposal meetings heldin Tokyo, Japan; Chicago, USA; and Glasgow,Scotland.These meetings provided informationto assist prospective applicants in preparingtheir proposals for experiments on theNeurolab mission. NASA received 172 respons-es in its call for research proposals—98 fromscientists in the US and 74 from other investi-gators around the world.

In March 1994, all proposals were reviewed fortheir scientific merit by United States and inter-national scientists. The review was managed bythe NIH.The proposals considered most meri-torious were later reviewed for their engineer-ing feasibility and appropriateness for the SpaceShuttle environment.Thirty-two proposals thatmet these criteria were selected, and the inves-tigators were assigned to Investigator Teamsbased on shared subjects, shared hardware, orcommon research themes.The teams weregiven ten months, called a Science DefinitionPeriod, to develop integrated research plans andprocedures that met their original scientificobjectives while maximizing the use of scarceShuttle resources. At the end of this period, theproposals were subjected to a second round ofreviews managed by NIH to ensure that the sci-entific value of the experiments remainedintact. Twenty-six proposals were assigned tothe Neurolab Spacelab mission and six weredesignated as small payloads to be flown onother missions because they could be conduct-ed in the mid-deck area on other Space Shuttleflights. However, all 32 investigations were des-ignated as the Neurolab Program.

Introduction Neurolab

Neurolab: A Special Space Mission toStudy the Nervous System



NEUROLAB PARTNERS

The Neurolab mission was remarkable for itsnational and international participation.TheNeurolab mission demonstrated how scientistsfrom around the world are able to work togetherto pursue scientific information that will benefitall people.The experience from Neurolab willbecome increasingly important as space life sci-entists spend longer periods of time conductingexperiments on the International Space Station.

International partners provided some majorpieces of equipment for Neurolab and fundingfor investigations from their respective nationalresearch teams. National partners provided fund-ing for the ground-based portions of Neurolabinvestigations that are relevant to their respectivemissions.The Neurolab Investigators cametogether at regularly scheduled meetings, calledInvestigators Working Group (IWG) meetings, todiscuss Neurolab experiments, to coordinate andintegrate their experiments, and to decide howtheir ground-based experiments would best bereplicated in space. NASA engineers and techni-cians had primary responsibility for ensuringthat all scientific and engineering elements of themission worked together for a successful launch.

SCIENCE TEAMS

Conducting scientific research onboard theSpace Shuttle is very different from doingresearch on Earth. All resources, such as electri-cal power, experimental supplies and space tostore them, work space, and crew time, arevaluable and limited commodities that must be judiciously allocated and shared by the investi-gations.

Four Neurolab science teams (Figure 10) car-ried out human investigations, and four con-ducted investigations on other animals.The

human investigation teams were managed bythe Johnson Space Center (JSC), located inHouston,Texas. Scientists on these teams exam-ined four areas of neuroscience: the autonomicnervous system (part of the nervous system thathandles automatic functions like breathing), cir-cadian rhythms and sleep, vestibular function(balance), and sensory/motor function and per-formance.The animal investigation teams, man-aged by the Ames Research Center (ARC), locat-ed in Moffet Field, California, included an adultneuronal plasticity (ability of mature nerve cellsto adapt) team, mammalian development, andaquatic and insect neurobiology teams.

USING ANIMALS IN RESEARCH

Physical space on the Space Shuttle was very lim-ited so all experiments were designed so theycould be accommodated in the Spacelab. Neuro-lab carried a variety of species, including rats,mice, swordtail fish, toadfish, crickets, andsnails, into space.The study of these animalshelped explain the role of gravity in develop-ment and other aspects of the nervous system.Some of the experiments complemented studiesconducted on the human crew; all were basedon important information from ground-basedexperiments.

Figure 10 Diagram of locations of the NASA centers that manage the Neurolab teams.




Experiences with animals in space laid the foun-dation for human space exploration and foradvancing understanding of changes that occurin cells and body systems in microgravity. Spacelife scientists increasingly use cell cultures andcomputer models to understand these changesand to ask new questions aboutliving systems in space. Animalmodels are used to examinechanges brought about by spaceflight on the brain, bones, mus-cles, heart, and other areas of thebody and to study developmen-tal biology when there are noother viable alternatives. Muchsignificant information aboutresponses of the body to micro-gravity also has come fromdetailed studies of astronautsthemselves, both during andafter space flight.

NASA, in consultation with apanel of ethicists from the ani-mal protection and regulatorycommunities, has developed andadopted a strict set of guidelinesfor animal care and use. Allresearch procedures involvinganimals must meet these regula-tions, which require that thefewest number and simplest ani-mals possible be involved. TheNASA Principles for the EthicalCare and Use of Animals weredeveloped around the belief thatthe use of animals in researchinvolves responsibility, not onlyfor the care and protection ofthe animals, but for the scientificcommunity and society as well.

THE CREW CONDUCTS SCIENCE IN SPACE

All space missions require years of dedicationand hard work from experts in a variety of disci-plines, and the Neurolab Shuttle mission was no

exception.While we often hearabout the incredible featsachieved by astronauts in space,we learn less about the role ofthousands of dedicated spaceengineers, technicians, technolo-gists, and administrators whomake the launches possible.TheNeurolab crew consisted of nineastronauts and scientists (Figure 11):

• One Commander

• One Pilot

• One Mission Specialisttrained and designated Flight Engineer

• Two Mission Specialists (astro-nauts), members of the Pay-load Crew and one of whomwas Payload Commander.

• Two Payload Specialists rec-ommended by the IWG andselected by NASA, who hadspecific qualifications appro-priate to the mission.Theywere not career astronauts andreturned to their respectivecareers after the mission.

• Two Alternate PayloadSpecialists, recommended bythe IWG and selected byNASA, who received trainingas Payload Specialists and wereprepared to become payloadspecialists if necessary.Theyalso had special roles duringthe mission.

Figure 11B PilotScott D.Altman

Figure 11C Mission SpecialistKathryn P. Hire

Figure 11D Mission SpecialistRichard Linnehan

Figure 11E Mission SpecialistDave R.Williams

Figure 11F Payload SpecialistJames A. Pawelczyk

Figure 11A CommanderRichard A. Searfoss

Figure 11G Payload SpecialistJay Buckey

Figure 11HAlternatePayload SpecialistChiaki Mukai

Figure 11IAlternatePayload SpecialistAlexander Dunlap


Introduction The Nervous System

OVERVIEW OF THE NERVOUS SYSTEM

Before studying the brain in space, it is helpfulto know something about the normal nervoussystem as it functions on Earth. What is the ner-vous system? What does it do? How does it doit? Of these three seemingly simple questions,the first two are reasonably straightforward, butthe third is much more difficult to answer.Neuroscientists have some ideas about what thenervous system does, but because there are somany levels of understanding, and because neu-roscience research is unfolding information sorapidly, our ability to describe how the nervoussystem processes information is constantlychanging. Aptly described as the final frontier ofbiology, neuroscience research is beginning toreveal some of the mysteries of the brain, thespinal cord, the specialized sense organs and thecomplicated network of nerves that togethermake up the nervous system.

The nervous system keeps usaware of our environment andallows us to react appropriatelyto external conditions. Forexample, if threatened, we useour senses—e.g., sight, smell,and hearing—to assess the levelof danger and to avoid, hidefrom, or confront the source ofdanger. But the nervous systemdoes much more than enable usto interact with our environ-ment by sensing and respond-ing to it. After all, we think,compose music, express love,

experience sadness, do mathematics, and evenstudy the brain.These are all nervous systemactivities that help to make us what we are. Howwe are able to perform these activities remainsone of the deeper mysteries of the nervous sys-tem.The best computers pale in comparison tothe human brain.Through the actions of ournervous system, we can carry out, sometimeswith little effort, a wide variety of tasks thatthus far have proven difficult, if not impossible,for machines.

Over the past thirty years, neuroscientists havemade tremendous inroads into the investigationof the nervous system and have begun to answersome of our more complex questions about it.

NeuronsThe basic signaling unit of the nervous systemis the nerve cell, or neuron (Figure 12), whichcomes in many different shapes, sizes andchemical contents.

The Nervous System

Figure 12 Diagram of a neuron. Adapted by permission(Purves, 1997)

Node of Ranvier

Myelin Sheath

Cell Body Motor End

Brushes

Neuron Cell

Nucleus




Information about the environment is gar-nered through sensory cells that are special-ized to respond to a particular external stim-ulus. In all sensory systems, the sensory cellgenerates an electrical signal in response tothe stimulus via a process called sensorytransduction. The electrical signals are for-warded to the spinal cord or brain, wherethey are processed and sometimes transmit-ted to effector organs, such as muscles orglands, to produce the appropriate response.

The general layout of neurons is fairly con-stant. Information is received on structuresknown as dendrites, transmitted to the cellbody and passed on via an axon which typ-ically ends on a dendrite of the next cell inline.The place where an axon contacts a den-drite or effector organ, such as a muscle orgland, is called a synapse (Figure 13).

The electrical signal in axons is a brief volt-age change called an action potential(Figure 14), or nerve impulse, which cantravel long distances, sometimes at highspeeds, without changing amplitude orduration.When an action potential arrives atthe end of the axon, it causes the release of astored chemical substance called a chemicalneurotransmitter into the synapse.The neu-rotransmitter can either increase or decreasethe probability that the next cell will fire anaction potential.When it increases the likeli-hood that the next cell will fire an actionpotential, the process is called excitation, thetransmitter is called an excitatory transmitter andthe synapse is an excitatory synapse. When itdecreases the likelihood that the next cell in linewill fire an action potential, the process is inhibi-tion and the transmitter and synapse are calledinhibitory.

The number of synapses that a given neuronmakes on another neuron or the effectiveness of a particular synapse in causing excitation or inhi-bition—synaptic efficacy—is not constant. In several cases, particularly during development,both the number of synapses and synaptic effi-

2+

Figure 13 Diagram of a Synapse. Adapted by permission (Purves, 1997)

Mem

bran

e P

oten

tial

(mv)

Figure 14 Diagram of Action Potential recorded from the cell body of a Purkinje neuron in the cerebellum.



cacy are altered. Scientists agree that oneimportant factor in determining number andstrength of synapses is the level of use of thesystem.The effect of use can be particularlystrong during a short window of time duringdevelopment called the “critical period.”Thetime at which the critical period occurs differsfrom system to system.These use-dependentchanges come under the heading of “synapticplasticity.” Some plastic changes last a shorttime—seconds to minutes—while others last along time—hours, days and even years. Ourability to learn and remember is a manifesta-tion of synaptic plasticity.

In certain systems, the nervous system respondsto changes that take place in such a manner as tokeep the system working more or less the same.For example, if the amount of neurotransmittersubstance released at a synapse is decreased, thenthe number of sensing molecules or neurotrans-mitter receptors at the synapse might increase toproduce about the same size response as before.The molecular mechanisms that are used todetect the changes and to make the appropriatealterations are not well understood. Space neuro-scientists have learned from past experimentsthat cells adapt at the molecular and anatomicallevels to the microgravity environment of space.Neurolab scientists conducted a series of experi-ments to further understand the molecular andanatomical bases of plasticity in neurons.

ANATOMY OF THE NERVOUS SYSTEM

Neuroscientists divide the nervous system intotwo components— the central nervous systemand the peripheral nervous system.The centralnervous system is comprised of the brain andthe spinal cord.The peripheral nervous systemincludes the sensory neurons that link the brain

and spinal cord to sensory receptors and effer-ent neurons connected to the muscles, glands,and organs.

The BrainThe brain is the most complex organ in thehuman body. It is comprised of the cerebrum,the brainstem, and the cerebellum (Figure 15).It is surrounded by three protective layers oftissue called the meninges, and bathed in liq-uid called the cerebrospinal fluid. This fluidalso protects the brain from injury and providesnourishment to its surrounding tissues.

The brainstem is a funnel-shaped structureconsisting of three components—the medulla,the pons, and the midbrain. These three struc-tures contain motor and sensory nerve cells thatreceive information from the skin and musclesof the head, and from the special sense organsof hearing, balance, and taste. Groups of nervecells in the brainstem control many of the auto-matic functions of our bodies, such as heart-beat, breathing, and digestion, as well as ouroverall alertness.

The cerebellum is divided into symmetricalhemispheres, right and left. The core of thecerebellum is made up of white matter, and theexterior is covered by grey matter called thecortex.The white matter gets its name from itswhitish appearance in fresh tissue and is due tothe presence of an insulating material calledmyelin. Grey matter is devoid of myelin and ismainly comprised of cell bodies of neurons andglial (non-neuronal) cells.The cerebellum isdivided into three parts, the cerebrocerebellum,which receives signals from the cerebrum, thevestibulocerebellum, which receives inputfrom the brainstem, and the spinocerebellum,which receives electrical signals from the spinal




cord (Figure 16).The surface of the cerebellumis shaped by thin folds, called folia.

The cerebellum coordinates motor activity, pos-ture, and balance, and helps us store informa-tion about motor skills such as the blink reflexand the vestibulo-ocular reflex (VOR).VORhelps us keep our eyes fixed on a visual targetwhile we move our head.

The cerebrum (Figure 15) represents 85% ofthe total weight of the human brain. It has ahighly convoluted surface, with ridges calledgyri and valleys called sulci. Neuroscientists andneurologists have mapped out the different areasof the cerebral cortex that control the varioussensory and motor activities of the human body.

Like the cerebellum, the cerebrum is dividedinto symmetrical hemispheres. Each hemisphereis divided into four “lobes,” the frontal, parietal,

temporal, and occipital lobes.These lobes havespecial functions.The frontal lobe is involvedwith planning and movement; the parietal lobewith sensation; the occipital lobe with vision;and the temporal lobe with learning, memory,and emotion.

The cerebral hemispheres surround an areacalled the diencephalon, which consists of thethalamus and the hypothalamus.The thalamusis a key structure of the cerebrum. It acts as agateway for sensory information coming fromthe major systems—vision, hearing and balance,taste and smell—to the corresponding sensoryarea of the cerebral cortex.

The hypothalamus regulates the autonomic ner-vous system, reproduction and homeostasis.Homeostasis is the process by which our bodiesmaintain a stable internal environment in theface of changing conditions. Many systems of

Figure 15 Diagram of the brain (sideview). Figure 16 Diagram of the brain (rearview).

Left Hemisphere

Parietal Lobes

Right Hemisphere

OccipitalLobes

CerebrocerebellumSpinocerebellum

Vestibulocerebellum

Cerebrum

Frontal Lobe

Parietal Lobe

Temporal Lobe

Occipital Lobe

Midbrain

PonsMedulla

Brainstem

Cerebellum



the body show rhythmic changes within a peri-od of approximately one day—circadianrhythms.The suprachiasmatic nucleus isthought to function as the body’s master biolog-ical clock and is located in the hypothalamus,which is a major part of the diencephalon.

The Spinal CordThe spinal cord lies in the vertebral canal and isprotected by the bony spinal column. In thespinal cord, the positions of grey and whitematter are reversed within the brain.The greymatter is on the inside, while the myelinatednerve tracts, that make up the white matter, areon the outside.

Thirty-one pairs of peripheral nerves originatefrom the spinal cord and spread throughout thebody. Sensory information carried by the affer-ent (incoming) axons in the peripheral nervesenters the spinal cord through the dorsal roots.Motor commands, carried by the efferent (out-going) axons, leave the spinal cord through theventral roots.

NEUROLAB SCIENCE AND THE NERVOUS SYSTEM

The Neurolab Shuttle carried twenty-six experi-ments that studied the effects of microgravity onthe following five aspects of the nervous sys-tem: developmental neurobiology; vestibularfunction; spatial orientation and visuo-motorperformance; autonomic nervous system regula-tion; and sleep and circadian rhythms.

Developmental NeurobiologyThe human brain and spinal cord are formedfrom dividing cells in the fertilized egg. In orderto form a fully developed brain and spinal cord,cells from the fertilized egg must undergo mito-sis, migration and differentiation. Mitosis is theprocess by which cells divide. Cell migrationrefers to the movement of cells from their birth-place to their final destination. Cell differentia-tion is the process by which developing cellsmature into their final specialized form.

Scientists believe that proper development of thenervous system depends upon precise timing ofmitosis, migration, and differentiation. In addi-tion, neural populations must form appropriateconnections to each other early in developmentor risk undergoing programmed cell death.Theperiod in which neural populations establishconnections with each other starts during earlyembryogenesis and can continue well into thepostnatal ages. Embryogenesis is a phase of pre-natal developmental stages.Thus, early and post-natal developmental stages are critical for nor-mal spinal cord and brain maturation.

The developing nervous system may interactwith gravity in ways scientists do not yet com-pletely understand. Neurolab scientists designedseveral experiments using a variety of animals tostudy the effects of space environment condi-tions on the development of the nervous sys-tem. For example, one such experiment lookedat the changes in size and neuronal connectivityof the gravity sensing organs in snail andswordtail fish. Another set of experiments stud-ied spatial learning acquisition in the rodenthippocampus, a specialized brain structureinvolved in learning and memory.




No Movement(Starting Line)

Acceleration(Running)

Deceleration(Finish Line)

Figure 17 Diagram of how the otoliths sense linear acceleration.

Vestibular FunctionMost living organisms have sensory receptorsfor sensing gravity and transmitting informationabout head and body orientation and motion. Invertebrates, including humans, this system iscalled the vestibular system.The vestibular sys-tem is made up of three semicircular canalsand the otolith organs of the utricle and sac-cule which are located in the inner ear.

The semicircular canals are primarily responsi-ble for sensing head rotation.They contain fluidand receptor hair cells that are encased in a deli-cate membrane called the cupula (Figure 18).Head movements cause the fluid to shift, there-by triggering the hair cells to send sensoryimpulses along the vestibular nerve to the high-er centers in the brain.The three canals are situ-ated roughly at right angles to one another inthe three planes of space.This allows the canalsto act separately and in combination to detectdifferent types of head movement. They detectwhen we nod in an up and down motion(pitch), when we tilt our head to the sidetowards our shoulder (roll), and when weshake our head “no” in a side motion (yaw).

The otolith organs are responsible for detectinglinear acceleration (Figure 17), movement ofthe head in a straight line (side to side, up anddown, back and forth). The utricle and sacculeare membranous sacs. On the inside walls ofboth the utricle and saccule, there is a bed ofseveral thousand hair cells, whose hair bundlesare covered by small, flat crystals.These crystalsare called otoliths, a word which means “earstones.” The utricle and the saccule are oftenreferred to as “the otolith organs.” When youhold your head in the normal erect position, thehair cells in the utricle lie in a horizontal posi-tion. When you tilt your head to either side, thehairs bend, thereby stimulating the hair cells tosend a signal to the brain about the amount ofhead tilt.

In the weightless environment of space, tiltingthe head does not stimulate the otoliths. Signalsfrom the otolith organs conflict with the semi-circular canals and the visual signals that arebeing sent to the brain.The microgravity envi-ronment of space affects astronauts in signifi-cant ways.They may experience dizziness, getspace motion sickness, and be unable to differ-



entiate up from down.They sometimes becomedisoriented because they cannot fully perceivewhere their limbs are located.

The Neurolab scientists developed several exper-iments to study why astronauts feel unsteady ontheir feet and experience difficulty with balanceupon return to Earth. One experiment correlat-ed spatial orientation with the axis of eye move-ment using an off-axis rotating chair capable ofproviding accelerations and decelerations. Byusing the measurements of astronauts’ eye

movements, scientists were able to determinehow spatial orientation of astronauts changedand how the vestibular system works in space.Studies on Earth have shown that movements ofthe eyes accurately reveal what happens in theinner ear.

Luckily for astronauts, the vestibular system isvery adaptable. After a few days in space, theastronauts float without discomfort. When theyreturn to Earth’s gravitational environment, theirvestibular system readapts over several days toits normal functions.

Spatial OrientationThe process by which we align, or position, ourbodies in relation to objects or reference pointsin a three-dimensional space is called spatialorientation.To maintain this sense of “wherewe are,” our somatic sensory system processessignals from our vestibular, visual, tactile, andproprioceptive (a sense of the movements andpositions of the limbs) systems.

In space, astronauts must maintain their spatialorientation without the “down” direction signalwhich gravity provides on Earth. Astronauts haveto adapt to the sensory disturbances producedby microgravity. Some depend heavily on vision,while others orient their bodies in relation toexternal references, such as equipment racks orthe floor of the spacecraft.

The Neurolab scientists designed a variety ofnovel technologies and tests to show how thischange takes place.The astronauts performed sev-eral experiments to determine how spatial orien-tation and movement is altered in space. These

Figure 18 Diagram of a receptor hair cell.




included a ball-catching test to see how the per-ception of moving objects changes in micrograv-ity; the use of a virtual environment system tostudy body orientation; and the study of theeffects of microgravity on pointing and reachingtasks. The information collected from theseexperiments provided insights into how the ner-vous system creates balance between informationit gathers from the eyes, inner ears, and joints.

The Autonomic Nervous SystemThe autonomic nervous system has two majordivisions—the sympathetic and parasympa-thetic (Figure 73).The main control center inthe brain for the autonomic system is the hypo-thalamus.The sympathetic system organizes andregulates the body’s response to stress. For exam-ple, sympathetic neurons enable blood vessels toconstrict, speed up heartbeat, dilate our pupils,stimulate secretion by our sweat glands, and pre-pare us to respond to emergencies— the so-called “flight or fight” reaction.The parasympa-thetic system organizes the body’s responses thatsave energy and balances the body’s various sys-tems. It slows the heartbeat, constricts the pupilsin our eyes, dilates or expands blood vessels,stimulates digestion, and generally prepares thebody for relaxation and rest.

These responses are called involuntary or reflexactions (Figure 19) because they occur automat-ically to integrate and coordinate the autonomicsystem’s responses.The microgravity environ-ment changes these responses, which may causeproblems for the astronauts. One problem isfeeling faint and light-headed shortly after flightbecause of low blood pressure. Since the auto-nomic control of circulation changes in amicrogravity environment, the Neurolab scien-tists studied how the regulation of functions,such as blood pressure and blood flow to thebrain is changed in space.

Sleep and Circadian RhythmsThere are daily rhythms to many of our bodilyfunctions. Many of these rhythms run on anappropriate 24-hour cycle that is called “circadi-an rhythm.” These rhythms persist, even if onelives in a dark place and does not know thetime of day. Circadian rhythms are closelylinked with sleep, and their disruption can easi-ly disturb sleep.

Scientists agree that the “master clock” for cir-cadian rhythms is located in the suprachiasmat-ic nucleus, which forms part of the hypothala-mus.The suprachiasmatic nucleus receivesinformation from our eyes, and this informa-tion is used to synchronize our circadianrhythms with sunlight.

Astronauts sometimes have trouble sleeping onShuttle Missions.The Neurolab scientists stud-ied the astronauts’ circadian rhythms to learnwhy sleep is disrupted in space.They alsoexamined the effectiveness of the hormonemelatonin (which is involved with sleep) as asleep aid, and studied how changes in breath-ing caused by microgravity, affected the astro-nauts’ sleep.

Doctor

Patient

Figure 19 Diagram of involuntary or reflex action.


Part II

Neurolab Lessons & Activities

The Scientific Method

Lessons and Activities

GRADES 5–12



The Scientific Method The Seven Steps

The Scientific MethodScientists aim to gain knowledge and reach an understanding of the worldaround us.To achieve this goal, scientists must be curious, make observa-tions, ask questions, and try to solve problems. Early scientists tended todraw conclusions from observations that were largely speculative (e.g., theEarth was flat or that the sun circled the Earth). By the mid-sixteenth centu-ry, some scientists began to realize that far more knowledge could beobtained by using a systematic approach to obtaining information and solv-ing problems.

One ground-breaking scientist was Andreas Vesalius (1514–1564), the firstphysician to write an extensive text about human anatomy based on metic-ulous dissections of human bodies. In 1620, Sir Francis Bacon published hisNovum Organum in which he attempted to provide a complete method forstudying science. From these early beginnings, the Scientific Methodevolved as an orderly, systematic process for solving problems.

By the mid-nineteenth century, Charles Darwin and other scientists werefollowing what has become the modern scientific method. According to thismethod, the first step is to speculate or create a hypothesis.The second stepconsists of carrying out experiments and/or making comparative observa-tions to test the hypothesis.

Steps of the Scientific Method

1. Identify the problem

2. Collect information about the problem

3. Propose a hypothesis

4. Test the hypothesis by conducting experiments, making comparative observations, and collecting data

5. Evaluate the data collected through investigation

6. Draw conclusions based on data and determine whether to accept or reject the hypothesis

7. Communicate results and ask new questions



The problem is a statement of the question to be investigated. Observationsand curiosity help to define exactly what problem should be investigatedand what question(s) answered. Once a problem is defined, a scientistshould collect as much information as possible about it by searching journals, books and electronic information sources.This information willprovide a basis for forming the hypothesis.

A hypothesis is often considered to be an “educated guess.”The word“guess” is inappropriate, however, because a hypothesis should be based oninformation gathered. A hypothesis can be defined more accurately as a“proposed answer to the problem.”The hypothesis is then tested throughexperimentation and observation.The results of experimentation provideevidence that may or may not support the hypothesis.

To be effective, experiments must be properly planned.The plan is calledthe procedure, which describes the things that actually will be done to perform the investigation.This is where decisions are made about whichvariables will be tested and which will be kept constant, what to use as acontrol, how many samples to use, how large the sample sizes should be,safety precautions needed, and how many times to run the experiment.Many scientists investigate questions that cannot be answered directlythrough controlled experiments in laboratories. For example, scientistsstudying global warming, the AIDS epidemic and losses of biodiversitymust use comparative methods to examine differences that occur in thenatural world.

When developing the procedure for an experiment, consider the following:

1. Test only one variable at a time.

A scientist wanting to find out “why trees shed their leaves in the fall”would have to consider the factors that affect trees, such as the type of tree,the amount of water they receive, the temperature, the length of daylight towhich they are exposed, and the type of soil in which they are growing.These are the variables which can cause changes to occur in an experiment.To obtain reliable results, only one variable should be tested at a time. Allothers should be kept constant, whenever possible.

If the scientist’s hypothesis states that shorter daylight hours cause trees toshed their leaves in the fall, trees of the same age should be tested.Theyshould be placed in the same size pots with the same type of soil, given thesame amount of water, and kept at the same temperature.The only thingchanged should be the number of hours of light to which different groups




of trees are exposed. Any variable that the experimenter chooses to change,such as the hours exposed to light, is referred to as the independent variable.The change in the experiment that happens as a result of the inde-pendent variable, such as the length of time that it takes for the leaves tofall, is referred to as the dependent variable.

2. Use controls.

The control is used for comparing the changes that occur when the vari-ables are tested. If a number of young oak trees are placed in a greenhouseand exposed to 10 hours of light to simulate fall conditions, how will thescientist know if a loss of leaves is due to the amount of light? It could bedue to the temperature that he/she chose, or the amount of carbon dioxidein the air.To avoid such uncertainty, two identical experiments must be setup: one in which the trees are exposed to 10 hours of light and the other,the control, in which they are exposed to light for a longer period of timeto simulate summer conditions. All factors for the control are exactly thesame as for the test, except for the variable being tested, the amount of lightgiven to each tree.

3. Use several samples.

Using a number of samples prevents errors due to differences among indi-viduals being tested. Some trees are more hearty than others. If only a fewtrees are tested, some may lose leaves for reasons that are not related to theamount of light.This will produce misleading results. Larger numbers ofsamples will provide more accurate results.

4. Always use appropriate safety measures.

Safety measures to be followed vary according to the type of experimentbeing performed. For example, laboratory-based experiments frequentlyrequire that participants wear protective clothing and safety goggles, andthat dangerous volatile chemicals be used only under a vented fume hood.

5. Repeat the experiment several times.

To make valid conclusions, the scientist must have reproducible results.Ideally, comparable results should be obtained every time the experimentis run.


After the plan, or procedure, is complete, the experiment is run. It isessential that careful and accurate records be kept of all observations dur-ing an experiment.The recorded observations and the measurements

comprise the data. It is always useful to present datain the form of charts, tables, or graphs, as these pro-vide a visual way to analyze and interpret the results(Figure 20). When drawing graphs, the independentvariable is conventionally plotted on the horizontalaxis, and the dependent variable is plotted on the ver-tical axis.

Analysis of data from the experiment allows the scien-tist to reach a conclusion.The scientist determineswhether or not the data support the hypothesis anddecides whether to accept or reject the hypothesis.The conclusion should provide an answer to the ques-tion asked in the problem. Even if the hypothesis isrejected, much information has been gained by per-

forming the experiment.This information can be used to help develop anew hypothesis if the results repeatedly show that the original hypothesesis inappropriate.

After performing many investigations on a particular problem over a periodof time, a scientist may come up with an explanation for the problem,based on all the observations and conclusions made.This is called a theory.A Scientific Theory is an explanation, supported by data, of how or whysome event took place in nature.

Students should be encouraged to understand that the scientific method can beapplied to solving everyday problems, such as “Under what conditions do I studybest?” or “What type of lunch box will keep my lunch coldest?” The activities in thismanual allow students to understand and experience many of the problems addressed,and hypotheses proposed, by Neurolab scientists. Activities, such as the Escher Staircase(Pages 95 – 99), simulate actual experiments that were performed on board Neurolab.It will be exciting for students to compare the results of the control experiments per-formed on Earth with the results of tests performed in space.


y

x

Data

Figure 20 Diagram of teacher using graph representing data.



The Scientific Method Learning Activity I

LEARNING ACTIVITY I:Introduction to the Scientific Method

OVERVIEW Students will learn to make observations,formulate hypotheses and design a controlledexperiment, based on the reaction of carbondioxide with calcium hydroxide.

SCIENCE & Making and recording qualitativeMATHEMATICS observations, drawing conclusionsSKILLS

PREPARATION 10 minutes to gather equipment; 30 minutes TIME to prepare calcium hydroxide solution

Preparation of one liter of lime water(Teacher should prepare a day ahead of time):

MATERIALS • 10 grams calcium hydroxide powder• One liter of water• Filter paper• Filter funnel• Large bottle (2 liters)• Flasks or small bottles

1. Add 10 grams calcium hydroxide Ca(OH)2 powder to one liter of water.

2. Cover and shake well. Calcium hydroxide is very slightly soluble in water and 10 grams will provide more solid than will dissolve.

3. Allow the suspension formed to settle for a few minutes.

4. To separate the lime water from the sus-pension, use a filter paper and filter funnelapparatus to filter the suspension.

5. If the lime water filtrate is still slightly cloudy, filter for a second time, using a new filter paper.

* Ca(OH)2 + CO2 CaCO3 + H2O

† CaCO3 + H2CO3 Ca++ + 2HCO3

MAJOR CONCEPTS

• Our exhaled breathcontains carbon diox-ide gas.

• The carbon dioxidewe exhale reacts withcalcium hydroxide insolution to form insol-uble calcium carbon-ate and water.*

• Formation of calciumcarbonate precipitatecan be used as a testfor the presence ofcarbon dioxide.

• If carbon dioxide con-tinues to be bubbledinto lime water (calci-um hydroxide solu-tion) after a period oftime, the white pre-cipitate disappears.Theexcess carbon dioxideforms carbonic acid inthe water and the cal-cium carbonate reactswith the carbonic acidto form calcium ionsand bicarbonate ions,which are soluble inwater.†

Ca(OH)2 = Calcium Hydroxide

CO2 = Carbon Dioxide

CaCO3 = Calcium Carbonate

H2O = Water

H2CO3 = Carbonic Acid Gas

Ca++ = Calcium



6. Keep the lime water tightly closed when not in use, as it will react with carbon dioxide from the air and become cloudy.

7. The calcium hydroxide and water suspension can be stored in a large bottle, and lime water filtered off when needed.

8. The filtered lime water can be stored in smaller bottles or flasks,500 milliliters in volume, for use in class. One (1) liter will be sufficient for one class of 24 students for days one and two.

CLASS TIME Two or three periods of 40 – 45 minutes

MATERIALSDay 1: Per student • 1 plastic test tube, 50 milliliters (ml) in volume

• 1 straw• 10 – 15 ml lime water solution (calcium hydroxide solution)• Goggles

MATERIALSDay 2 and Day 3: The materials will vary depending on the design of the students’ experi-Per student ments. All students will require test tubes, lime water, foil, and straws.

BACKGROUND Carbon dioxide comprises only 0.033 percent of Earth’s atmosphere, yet itis the principle inorganic source of carbon for living organisms. Carbondioxide and water are the raw materials required by plants for the synthesisof sugars through photosynthesis. Organisms release carbon dioxide backinto the atmosphere as a waste product of respiration and other cellularprocesses.

This activity allows students to test for the presence of carbon dioxide inexhaled air. On Day 1, each student will blow through a straw into a solu-tion of calcium hydroxide.The carbon dioxide in the air will combine withthe calcium hydroxide to produce a white precipitate of calcium carbonate.Students will compare their solutions to those of the teacher, in which aprecipitate will not be visible. (Students will not immediately be able toobserve that if they continue to blow into the calcium hydroxide solution,the white precipitate will disappear.) Students will then generate hypothesesto explain the divergent results.

The second part of this activity (Day 2) involves designing an experiment to test the hypotheses determined in the class discussion on Day 1. It maybe handled in different ways depending on the age of the students.




GRADES 10–12 For homework, have each student (or team of students) formulate ahypothesis to explain why they had a precipitate and the teacher did not.They should design a simple controlled experiment to test the hypothesis.On Day 2, review students’ procedures and allow them to perform theirexperiments, record their observations and draw conclusions. Grades 10 –12 should be able to complete the activity in two days, grades 5 – 9 inthree days.

GRADES 7–9 Have students work in groups of three to four to formulate a hypothesisabout the disappearance of the precipitate and design an experiment to testthe hypothesis. Encourage each group to investigate a different variable.Thehypothesis and procedure proposed by each group should be presented tothe class and discussed, based on the questions on pages 41 – 42 under Day2.The students will then run the experiments they designed on Day 3.

FOR GRADES 5–6 Before proceeding, have the whole class participate in a teacher-directed dis-cussion to determine possible hypotheses about the precipitate and how todesign experiments to test each hypothesis.This will help to prepare themto conduct their experiments the next day.

Note to Teacher: The students’ answers to the discussion questions will vary, depending on thehypothesis tested and the design of the experiment. The questions are intended to be a checklist to help students determine whether or not they have designed a valid experiment.

DAY 1

PROCEDURE 1. Explain to students that it is important for scientists to make careful observations, and inform them that they will practice making observations.

2. Direct each student to fill a test tube with 15 ml of the calcium hydrox-ide solution that you have prepared in advance and to use a straw to bubble their breath into the liquid slowly. (Make sure that the solution is clear.) Caution them against blowing into the liquid too vigorously.

Note to Teacher: For grades 5 and 6, the test tubes of liquid could be set up ahead of time.Students should wear goggles while bubbling into the solution.

3. Have the students observe the solution after blowing through the straws for approximately 1 – 2 minutes. Students should record their observations in their notebooks. Explain that these observations will make up students’ data.

Note to Teacher: Most students will get a white precipitate and stop bubbling.Those in higher grades may know exactly what happened.



4. Use the following questions as a basis for a class discussion.

• What gases are present in exhaled air?Carbon dioxide gas (nitrogen, water vapor and small amounts of oxygen are also present).

• What is the clear liquid?Lime water

• How can we test for the presence of carbon dioxide?Bubble the gas into the lime water.

• What is a positive test for carbon dioxide?Carbon dioxide turns clear lime water cloudy.

• Why is a precipitate formed?Lime water is a solution of calcium hydroxide. It chemically reacts with carbon dioxide to form solid calcium carbonate (chalk).

5. When the students are convinced that they know exactly what happened, bring out the “teacher’s results.” Explain that you did the exact same experiment, but got very different results! Your test tube hasno white precipitate—it is clear. The class now has a problem to solve:How can there be no white precipitate when the teacher performed the same experiment?

6. Discuss with students what fac-tors might affect the produc-tion of a precipitate. (DO NOTtell the students how youobtained your results.)

Possible answers might be:

• Time—how long exhaled air was bubbled into the solution.

• Adults vs. teenagers.

• Rate of bubbling.

• Light vs. dark.

• Temperature of the liquid.

• Any other conditions at time of breathing.

7. Explain that all of the factors identified by students are known as variables.

Figure 21 Diagram of teacher-directed discussion with class.




DAY 2

PROCEDURE 1. Use the following questions to guide students or groups of students in the development of their hypotheses and experimental designs.

• Does the hypothesis offer an answer to the problem?Yes it does.The problem was, “Why was there no white precipitatewhen the teacher performed the experiment?”The hypothesis states that the teacher may have exhaled into the solution for a longer timethan the students.

• Does the experiment have a control?Yes.The control is the average length of time that the students exhaledinto the solution of lime water (possibly about one minute).

• Which materials are needed? Are the materials readily available?

• What conditions are being kept constant?The conditions kept constant are the temperature of the liquid, the sizeof the straws, the rate of bubbling into the liquid and the amount oflime water used for each test.

• What is the independent variable being tested?This is the variable that the experimenter chooses to change.In the example given, it is the increased length of time that the students choose to exhale into the lime water.

• What is the dependent variable being measured?The dependent variable is the amount of precipitate present after exhaling into the tube of lime water.

• How will each group present its data?The data may be presented in the form of a chart (Figure 22).This can be indicated by using + to represent the density of the precipitate.

DAY 3

1. Allow individuals or teams of students to perform their experiments,collect data and draw conclusions. A post-experiment discussion is recommended to review the conclusions made by each group. Each group’s experiment should be evaluated based on the appropriateness of the experimental design to test the group’s hypothesis (not whether the group actually found the “correct” solution).

Figure 22 Sample of data sheet forrecording precipitate.

Exhale Time Amount of(observations) Precipitate

0.25 min. +

0.5 min. ++

1.0 min. +++

1.5 min. +++

2.0 min. +++

2.5 min. +++

3.0 min. ++

3.5 min. ++

4.0 min. +


2. For a typical experiment to test the hypothesis that “the length oftime that air was blown into the solution” caused the teacher’s resultsto be different, each student in a group of four should use the same size tube, the same amount of lime water, run the experiment at the same temperature, use the same size straws and attempt to bubble at the same rate. Students could estimate how long they exhaled into their liquid the first day.This could be the control time. One student in each group could blow into his/her tube for the control time. Each following student in the group could increase his or her time by two to four minutes.

POST-LAB 3. Compare the experiments performed by each group of students. ForDISCUSSION each experiment designed, discuss the variable tested, the control, the

factors kept constant, and the results obtained. Note that the amount oflime water used, and the size of the straws and test tubes should be thesame for each experiment. A chart, such as the one below, can be devel-oped on an overhead projector.

* Cover test tube with foil to create darkness.

4. From the class observations, it can be seen that only the length of timeaffects the amount of precipitate formed. At this point, explain that excesscarbon dioxide bubbled into lime water forms carbonic acid which dis-solves the precipitate of calcium carbonate.

The use of the scientific method to systematically test different hypotheses willenable the students to determine which hypothesis is correct in answering a problem.


Independent Control Constants ObservationsVariable Tested

1. Length of time breath was 2 mins. Room temperature The precipitatebubbled into the solution Bubble slowly formed, increased,(from .25 mins. to 4 mins.) Keep tube in the light then decreased

2. Temperature of Room Bubble for 2 mins. Precipitate formed,the water (warm/cold) temperature Bubble slowly did not decrease

Keep tube in the light

3. Rate of bubbling Bubble Room temperature Precipitate formed,(slowly/quickly) slowly Bubble for 2 mins. did not decrease

Keep tube in the light

4. Amount of light (light/ Keep tube in Room temperature Precipitate formed,dark)* the light Bubble for 2 mins. did not decrease

Bubble slowly

Figure 23 Example of chart comparing experiments.


Developmentaland CellularNeurobiology


GRADES 5–12

Section I



Developmental and Cellular Neurobiology Introduction

Developmental and Cellular Neurobiology

TOPIC Recent studies have shown that microgravity has an effect upon normaldevelopment and function of nerves and muscle.

How will prolonged space flight alter development and normal func-tion of the human neuromuscular system?

INTRODUCTION The human body is composed of three muscle types: skeletal, smooth,and cardiac muscles (Figure 24). Skeletal muscle controls all voluntarymovement, such as walking, sitting, or throwing a ball. Smooth musclesperform unconscious or involuntary motions, such as moving foodthrough the digestive system. Cardiac muscle is heart muscle which isresponsible for pumping blood through the body. All three muscle typesdiffer from each other in how the nervous system transmits signals tothem and in the types of molecules present within the muscle cells.

Skeletal muscles that are involved in standing and walk-ing are referred to as weight-bearing muscles. Scientistsbelieve weight-bearing muscles are profoundly affectedby exposure to microgravity. Weight-bearing muscles alsoconsist of two different fiber types known as slow (orred) and fast (or white) twitch muscles. The two differ-ent muscle types are involved in specialized types ofmovement and activity of neurons of the central nervoussystem are believed to influence which type of fiber themuscle will become.

The capacity to perform detailed experiments on bothhuman and animal subjects in space provides fascinatingopportunities to investigate functional changes in theabsence of gravity’s effects. Is gravity necessary for nor-mal development and function of skeletal muscle? Doesthe nervous system require gravity to make functionalcontact with weight-bearing skeletal muscle correctly?Does gravity alter the manner in which the nervous sys-

tem communicates with muscle? Experimental research can provideinvaluable information about the underlying mechanisms of gravity’seffect upon human physiology.The Neurolab team investigated how spaceflight and microgravity affect the nervous system and its interaction withskeletal muscle.

Skeletal

Cardiac

Smooth

Figure 24 Diagram of three muscle types.



Things to Know

OVERVIEW OF Weight-bearing muscles are attached to the bones of the body by tendons.THE SKELETAL Both slow twitch (red) and fast twitch (white) weight-bearing muscles NEUROMUSCULAR control body movement by contraction (becoming shorter).The muscles SYSTEM contract as a result of signals from neurons that are connected to

the muscle fiber.

Neurons are the basic unit of the nervous system (Figure 25). Each neuronconsists of a cell body with extensions that either send information (axon)or receive information (dendrite). Neurons that send contraction signals tothe muscle are known as motor neurons and are located in the spinal cord.The motor neuron’s axon reaches skeletal muscle early in development and

forms a specialized connection known as the motor end plate (Figure 25).Scientists believe that axonal signals transmitted from motor neurons to themuscle fiber will determine whether the muscle fiber will become either aslow twitch or fast twitch type. Slow and fast twitch muscles manage differ-ent types of motion necessary to function in gravitational fields.

Slow twitch (red) muscles have a rich blood supply and are capable ofendurance activities, such as marathon running or standing for prolongedperiods. In contrast, fast twitch (white) muscles have a more limitedblood supply and are specialized for very fast contractions and forcefulmovements like lifting heavy weights. In addition, fast twitch musclesfatigue easily. Exposure to microgravity will cause both slow and fasttwitch weight-bearing skeletal muscles to shrink. However, slow twitchweight-bearing muscles appear to be more vulnerable to microgravity.

Figure 25 Diagram of a neuron cell.

Dendrite

Node of Ranvier

Myelin Sheath

Cell Body Motor End

Plates

Neuron Cell

Nucleus



DEVELOPMENT Motor neurons make connections with muscles early in development.The OF THE ability of the neuron to find the muscle and make a connection (synapse) NEUROMUSCULAR is highly controlled by signals present during the developmental period.SYSTEM When the neuron first contacts its target muscle, it will make more

synapses than it requires. Once the muscle matures, the extra synapses areeliminated and the muscle will become either a slow or fast twitch fiber.Maturation into either a slow or fast twitch fiber will determine whetherthe muscle can perform such functions as standing for prolonged periodsin a normal gravitational field or briefly lifting a very heavy weight.

How does microgravity affect neuronal function?

Scientists are studying how microgravity will affect developmental signalsfrom the neuron to the muscle. It is possible that gravity is required forthe neuron to form functional motor end plates and behave normally.

The development of motor skills, such aswalking, requires maturation of the neuro-muscular system. As these systems developand become more coordinated, the ability towalk develops over a definite sequence ofmilestones: the baby lifts its head, then suc-cessively supports its body with its arms,turns over, sits up, crawls then walks withassistance (Figures 26A, 26B and 26C).Finally, the baby learns to walk alone. Thissequence occurs as muscle and bone strengthincrease and the nervous system becomes cal-ibrated to control the timing and strength ofmuscle activity and interpret the incomingsensory signals. Just as one must practicebaseball or the piano to play well, it is alsonecessary to practice to learn how to stand up,walk, jump, and run.

At each step in the process of learning tomove in a coordinated fashion, the baby isdeveloping in the presence of Earth’s gravity.In microgravity, important developmental sig-nals from the neuron to the muscle may bealtered during the critical developmental peri-od making it difficult for this motor system todevelop. Experimental studies in microgravitywill help scientists determine what role grav-ity plays in the normal development ofhuman neuromuscular systems.


Figure 26A Diagram of baby supporting body with arms.

Figure 26B Diagram of baby crawling.

Figure 26C Diagram of baby walking alone.

DEVELOPMENT OF MOTOR SKILLS


Developmental and Cellular Neurobiology Learning Activity I

LEARNING ACTIVITY I:What Cells Can I See

in Muscle and Spinal Cord Tissues?

OVERVIEW Students will observe, on a prepared slide, cellsof muscle and spinal cord tissues.

SCIENCE & Observing, comparing, describing,MATHEMATICS drawing conclusionsSKILLS

PREPARATION 10 minutesTIME

CLASS TIME 50 minutes

MATERIALS Each student or group of students will need:

• A compound light microscope• Prepared slides of skeletal muscle and spinal

cord tissues (preferably a cross section and longitudinal section)

BACKGROUND The body’s motor systems require specialized cells to perform coordinatedmovement. Skeletal muscle cells fuse during development, forming cylin-drical fibers. As a result, muscle fibers are multinucleated (more than onenucleus).The motor neuron sends an axon out of the spinal cord throughthe nerve and attaches to the muscle to form a motor end plate.

The Neurolab scientists attempted to identify the primary changes thatoccur in motorneurons and muscle fibers in the microgravity environ-ment.They conducted experiments with frozen, stained muscle fibers andspinal cord tissue from rats that were flown into space.To conduct theseexperiments, the microscope was used to examine histological sections ofmuscle fibers and spinal cord tissues. Analysis determined whether thefibers were smaller or whether the neuronal cell body was altered.

This activity will allow you and your students to observe cells in muscle and spinal cord tissues under the microscope.

MAJOR CONCEPTS

• To distinguishbetween cell typesthat make up spinal cord andmuscle tissues.

• To observe and dis-tinguish the nucleiof cell types andhow nuclei differbetween musclecells and motorneurons.




PROCEDURE 1. Students should be familiar with using the microscope (Figure 27)before carrying out this activity.

2. Divide class into groups of 2 – 4 students. Each student group shouldhave one microscope, which they should check to make sure is cleanand working properly.

3. Give each group five prepared slides. Eachgroup should have one slide of rat muscletissue and four slides of rat spinal cord tis-sue regions.

4. Instruct the students to use two differentmagnifications and sketch the cells theyobserve on a copy of the Student ActivitySheet at the end of this activity. Studentsshould record the magnification used foreach sketch.

5. Have students find and label the nuclei andthe cytoplasm for each tissue. Also havethem identify and label all other parts of thecells.

6. Make overhead transparencies or photocopies of the photographs(Figures 28 and 29) and allow students to compare their sketches tothe photographs. Ask students to describe as many differences and sim-ilarities between the cells in the two tissues as possible. Have themreport the number of cells that were observed of each tissue type.

Figure 29 Photograph of a magnified smooth muscle cell (x248).

Lens

Body Tube

RevolvingNosepiece

Objectives

MechanicalStage

Stage

Mirror

Rack and PinionSubstage

Course FocusingMechanism

Arm

FineFocusingMechanism

Base

Figure 27 Diagram of a microscope.

Figure 28 Photograph of a magnified spinal cord cell (x200).



EvaluationREVIEW QUESTIONS 1. Describe the shapes of muscle cells.

Muscle cells are elongated in shape.The nuclei are fairly uniform.

2. Do muscle cells look different from spinal cord cells? How do they differ?Yes.The muscle cells are elongated cylinders and the spinal cells aresomewhat circular.

THINKING 1. If the Neurolab scientists found differences in shapes and/or sizes of CRITICALLY these types of cells during their mission, what might this mean about

microgravity?If the Neurolab scientists found differences in shapes and/or sizes, itmay indicate that microgravity had affected the development or matu-ration of these cells.

2. How do you think microgravity may affect human muscle and spinalcord cells?Microgravity may affect human muscle and spinal cord cells by chang-ing the number of cells during the cell division stage of developmentor by altering the shape and size during change in development.

SKILL BUILDING 1. Obtain slides of human skeletal muscle and human spinal cord tissuesand have students compare these to rat tissue.

2. Obtain slides of cardiac and smooth muscles for students to observe.Have them compare these to the slides of skeletal muscle.

Note to teacher: Prestained slides may be obtained from:Science Kit & Boreal Laboratories Muscle tissue, cat. #69178-05Phone: 1-800-828-7777 (price: approximately $6.00 ea.)Fax: 1-800-828-3299 Spinal cord tissue, cat. # 69242-03www.sciencekit.com (price: approximately $5.00 ea.)

Wards Natural Science Muscle tissue, cat. #33W3542Phone: 1-800-962-2660 (price: approximately $6.00 ea.)Fax: 1-800-635-8439 Spinal cord tissue, cat. # 93W3699www.wardsci.com (price: approximately $5.00 ea.)



Developmental and Cellular Neurobiology Student Activity Sheet: Learning Activity I

STUDENT ACTIVITY SHEETWhat Cells Can I See?

Name ________________________________________________ Date __________________

OBJECTIVE To compare and contrast the cells of smooth muscle and spinal cord tissues.

DIRECTIONS Obtain a group of prepared slides from your teacher.The teacher will giveyour group a microscope (Figure 30) for you to observe the cells on theprepared slides.

PROCEDURES 1. Your group should have one microscope. Check to make sure that the microscope is clean and working properly.

2. You should have five prepared slides. One slide of rat smooth muscle tissue and four slides of four regions of rat spinal cord tissue.

3. Use two different magnifications and sketch the cells you observe.Record the magnification used for each sketch. (First use the lowest magnification lens, then rotate to the next magnification.)

4. Find and label the nuclei and the cytoplasm for eachtissue. Also identify and label all other parts of thecells.

5. Compare your sketches to the photographs or trans-parencies provided. Describe as many differencesand similarities between the cells in the two tissuesas possible. Report the number of cells that youobserve of each tissue type.

6. After you have completed the muscle tissue, repeatprocedures 3 through 5 using the four regions ofthe spinal cord tissue slides.

Figure 30 Diagram of student looking through a microscope.



Page 2

Name ________________________________________________ Date __________________

Muscle Tissue

MAGNIFICATION 1: ____________________ MAGNIFICATION 2:____________________

Diagram of muscle (sketch) Diagram of muscle (sketch)

Descriptions of number, shape, and size of cells: ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________



Page 3

Name ________________________________________________ Date __________________

Spinal Cord Tissue Region 1




Descriptions of number, shape, and size of cells: ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________



Page 4

Name ________________________________________________ Date __________________





Descriptions of number, shape, and size of cells: ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________




Developmental and Cellular Neurobiology Learning Activity II

LEARNING ACTIVITY II:Target Recognition and Synapse Formation

During Development

OVERVIEW Students will learn that growing axons makemore connections than they require duringdevelopment and will maintain only those con-nections necessary for correct neuromuscularfunctioning.

SCIENCE & Inferring, problem-solving, observing,MATHEMATICS drawing conclusionsSKILLS



MATERIALS Each team or group of 10 – 16 students will need:

• Five – eight sections of colored string (each adifferent color and cut 10 – 20 feet long)— one piece for every two students on the team.

BACKGROUND This lesson focuses on neuron/target muscle recognition in neural devel-opment.The axon is the long filamentous part of a neuron leading awayfrom the neuronal cell body.The end of the axon is subdivided into manyfilaments, which form the motor end plate (Figure 25). When messagesare transmitted, an impulse flows from the neuron to the target muscle.Only those synapses which are utilized continuously to perform maturemotor functions are maintained.

The importance and relevance of gravity’s influence on target recognition and synapse formation can be determined through investigations of target selection in space.

MAJOR CONCEPTS

• Axons must beable to form per-manent connec-tions (synapses)with their targets.

• Growing axonsmust be able tofind and identifyproper target cellsduring develop-ment.



PROCEDURE 1. Arrange students in two rows (row A and row B), facing away fromeach other, with equal numbers in each row. Make sure that the stu-dents use string long enough to account for tangling in the middle, asshown in Figure 31. Students in row A will represent axonal growthcones. Students in row B will be target muscles. The appropriate targetof each student in row A will be the row B student directly behindhim/her.

2. Give each student in row A an end of one of the cut strings.

3. Give the other end of each string to a student in row B. Make sure thatnone of the strings go straight across to the “proper” student. No cor-rect connections should exist at first, and the strings should be crossedat the outset (Figure 31).

4. To begin, have the first student in row A (the axonal growth cone) tugon his/her string to simulate the axon searching for its target cells. Thestudent in row B with the other end (an improper target) will notknow whether the person tugging is the proper neuron or not.

5. You or another student will act as an observer and provide informationabout whether the string is connected to the proper target by answer-ing either “yes” or “no,” when the row A person tugs on a string. (Aproper connection is made when the students across from each otherare holding the same colored strings.) If the feedback is “no,” ask thestudent in row B to switch strings with the student next to him/her.

6. Have the first student repeat his/her tug until enough switches havebeen made to find the “proper” target and elicit the “yes” feedbackfrom you (or the observer).

Figure 31 Diagram of students demonstrating proper axonal/target connections.

Note: Strings can be tangled in the middle as long as students directly across from each other end up holding the same color.

Shouldconclude

Row A Row B




7. Direct the next student in row A to tug, and repeat the process.

Note to Teacher: The strings in between the student rows will become tangled.This is fine. Inreality, neurons are arranged in bundles called nerves. Crossing will inevitably occur, but sincethe same colored strings eventually will be held by the students across from each other, studentswill understand that despite their potentially confusing path, the proper connections are made.

8. Have the students try the same procedure, but without saying “yes”or “no.” (This exercise will prove that the correct connections cannotbe made without proper recognition.)

EvaluationREVIEW QUESTIONS 1. What is required for axons to properly connect to their targets?

Axonal growth cones are required to specifically recognize the appro-priate target.

2. What happens when any part of the system breaks down?If a part of the system breaks down, improper functioning of the sensory system may occur.

THINKING CRITICALLY 1. How might microgravity affect the connections made?

Microgravity may cause binding at improper sites.

2. Is there point-for-point correspondence between neurons originat-ing in a certain area and their target areas?Yes.There is point-for-point correspondence because the neurons giverise to the axonal growth cones that specifically form connections totarget sites.

3. How are the specific connections made and maintained?Specific connections are made by forming stable connections throughtarget binding.

SKILL BUILDING 1. Have each student in row A record the number of attempts before connecting with the appropriate student in row B.Have students share their data and compute a class average of the number of attempts necessary.

2. Have students create another signaling system for guiding theconnection process in the model.


Developmental and Cellular Neurobiology Learning Activity III

LEARNING ACTIVITY III:Motor Skills Development

OVERVIEW Students will construct a timeline of thedevelopment of motor skills in humans bypooling observations of children of differentages.They also will construct an autobio-graphical account of their own development.

SCIENCE & Making and recording qualitative and MATHEMATICS quantitative observations, creating charts SKILLS and tables, drawing conclusions

PREPARATION NoneTIME

CLASS TIME 30 minutes to explain the activity, whichrequires one week of observation

MATERIALS Each student will need:

• Note pad• Pencil or pen• Tape recorder (optional)

BACKGROUND Neurolab experiments tested the hypothesisthat gravitational fields are necessary duringcritical periods of mammalian postnataldevelopment (development after birth) forthe normal sequence of motor system devel-opment to occur. This hypothesis suggestedthat space rats (and people) would turn outdifferently than Earth rats (and people) ifthey were weightless during certain criticaltimes during their development. Neurolabscientists also used information about nor-mal motor system development to make comparisons with development ofmotor skills of rats under microgravity conditions.

MAJOR CONCEPTS

• Critical periods existduring the develop-ment process in whichwe must interact withour environments fordevelopment toprogress normally.

• There is a sequentialdevelopment of motorskills that takes placeover time (e.g., from ababy lifting his/herhead, to supportinghis/her body withhis/her arms, to turn-ing over, to sitting up,to crawling, to walkingwith assistance, andfinally, to walkingalone).

• The nervous systemaccounts for the effectsof gravity during the“programming” of themotor system.




Reflexes in Babies

The first steps of the investigation will be to find out the ages of babiesand children in each student’s family and, if possible, in neighboring fam-ilies. Based on information available to different class members, the groupshould be able to choose children of different ages to observe. Using thepooled observations made by students, each student or the class as awhole should be able to apply their observations and make a chart, or“timeline” of normal human development.

Should be elicited by a parent and observed by the student.

GRASP REFLEX The grasp reflex is the easiest baby reflex toobserve. If pressure is placed on the baby’shand or foot, the fingers or toes will curl up.The baby will hold tightly onto a finger (Figure32).

RIGHTING REFLEX This is a good example of the nervous systemdeveloping before muscles do. When a baby isplaced in a sitting position, he/she will try tokeep his/her head straight. If the neck musclesare not strong enough, the baby will needsome help. When the neck muscles develop,the baby will be able to hold his/her head up.

STARTLE REFLEX This reflex can be elicited by an unexpectednoise. After hearing a loud noise, a baby’s armsand legs move together, then out, then up, thenin. At the same time, the hands and legs openand close.

STEPPING REFLEX If a baby is held under the arms while his/herfeet are touching a solid surface, the baby willlift one foot up and put it down, followed bylifting the other foot (Figure 33). The samereflex can be observed if the baby’s feet arepressed against a couch. This reflex is seenfrom birth to about six to eight weeks of age,and again between eight and twelve months.

Figure 33 Diagram of stepping reflex.

Figure 32 Photograph of grasp reflex.


Developmental and Cellular Neurobiology Learning Activity III: Part One

TONIC NECK If the baby is lying on his/her back and not crying and his/her head is REFLEX turned to one side, often the arm on the same side will extend while the

leg on the other side will flex (Figure 34).This is the same position yousee when a right-handed baseball player extends his/her arm up to catcha ball. His/her head will be turned to the right, the right leg will be

extended, and the left arm and leg will be bent.

For older students, this activity can be extended to include the studyof the development of language among children of different ages.The main objective of the activity is to gather information by obser-vation and to learn that there is a time-related course of humandevelopment. Students also will learn whether the development ofcertain skills depends on strength, the nervous system, or both, andif development progresses in a front-to-back, head-to-tail, or othersequence. Over the course of the activity, students will observehuman development, take a “family history” from their parents, andwrite an autobiography.They will then compare the accuracy ofwhat they learned about human motor development by directobservation, “hear-say” information, and memory.

Note to Teacher: It is important to emphasize that growth and development is a continuous process and that milestones arenot reached at a particular age, but over a range of ages.

PROCEDURE Part One: Observing Development

1. Survey the students in the class to determine the numbers and ages of each student’s siblings (and younger friends and neighbors). From the list provided, choose babies, toddlers, and children (up to about seven –eight years of age) to include in the activity and to be observed by different members of the class. Suggest to the students that their parent(s) or guardian(s) provide this information.

2. Assign students or groups of students to observe babies, toddlers andyoung children from the list during the course of the following week.

3. Tell the students to observe their subject(s) carefully, take notes and fillout the class survey sheet, listing development skills and reflexes (seeStudent Activity Sheet on page 50).

4. If this activity is extended to language development (which may be themost interesting for high school students), tape recorders may be used todocument sounds.

5. Based on the class data, have each student or group of studentsdescribe the timeline of the acquisition of motor (and language, ifapplicable) skills in children.

Figure 34 Diagram of tonic neck reflex.



Developmental and Cellular Neurobiology Student Activity Sheet: Learning Activity III

STUDENT ACTIVITY SHEETObserving Development of Younger Subjects

Name ________________________________________________ Date __________________

1. What are the “vital statistics” of your subject?

______ weight ______ number of siblings______ height ______ position in family (what number child?)______ weight and length at birth ______ twin______ gender

2. Can your subject do the following? Place a check next to each action your subject can perform.

Movement

______ lift head ______ sit up with support______ hold head up and look around ______ sit up without support______ support body with arms ______ reach and pick up a toy______ roll over ______ crawl______ grab something, hold onto it ______ crawl up stairs

Awareness of Self and Others

______ follow family members with eyes ______ recognize own name______ smile ______ point at things______ laugh ______ wave good-bye______ recognize self in mirror ______ copy sounds______ recognize hands ______ say first words______ recognize feet

Walking______ stand up from sitting or crawling position ______ jump on one foot______ stand without falling, if holding onto something ______ hop______ stand alone ______ skip______ walk while holding onto something ______ jump______ walk alone ______ run______ stand on one foot ______ walk up stairs

Skilled Movement______ eat with a spoon ______ throw a ball straight ______ catch a ball (if so,______ drink from a cup ______ draw a straight line what size ball?)______ drink from a glass ______ make a circle around a drawing of a house______ use a knife and fork ______ copy a circle, triangle or drawing of a house

3. How many different kinds of controlled movements can your subject make? __________Add from above.


Developmental and Cellular Neurobiology Learning Activity III: Part Two

Part Two: Autobiographies

1. Have students fill out developmental surveys (as before) about theirown development with their parent(s)’ or guardian(s)’ help (pediatri-cians often have this type of information from “well child” exams). SeeStudent Activity Sheet on page 53.

2. Student should identify the sources of their information (e.g., self, par-ent, doctor, document, etc.).

3. Have each student use his or her own developmental surveys to createan autobiographical description of his or her own development frombirth until age six.

Evaluation

REVIEW 1. Are motor skills acquired in a particular sequence during development?QUESTIONS The acquisition of motor skills follows the development of the nervous

system.The nervous system, as well as motor skills, develops from thehead down. Babies can control their arms before their legs.This isbecause the motor cortex, which controls fine movements, developsover a roughly three-month period from 4 – 7 months. The develop-ment of sensory ability, such as improved vision is due to developmentof the connections between the retina and the brain.

2. What determines the sequence? Is it influenced by age, weight or gender?The sequence is determined by the growth of the nervous system.Since strength is also important, developments of the muscular system also plays an important role.

For the purposes of this discussion, the sequence is not influenced by gender (although girls and boys develop particular skills at different rates). Weight only plays a role in the case of underweight babies—malnutrition can delay development.

3. Is there a difference between what one observes and what oneremembers? Why?Yes. Relying on memory can be worse than not remembering at allbecause memory can be selective—we only remember some aspects ofour experiences. Also, memory can be incorrect or inaccurate becauseit is influenced by emotion, by what we expect, or by what we want toremember.




THINKING 1. If available, have students bring in pictures of themselves between the CRITICALLY ages of 0 – 2 years and put the photos on a board. Have students use

their data bases (Student Activity Sheet: Observing Your OwnDevelopment) to try to guess the ages of their classmates in each of thepictures (Figure 35).

2. Is knowledge of the subject’s age usefuldevelopmental information? Does thisrequirement vary according to the overall ageof the subject (e.g., each hour, day, week,month, or year)?

3. What might happen to a person that devel-oped under microgravity if he/she wereexposed to conditions of increased gravity,such as Earth?

The purpose of the Neurolab experimentswas to gather data that would help usanswer this question. However, there weresome hints from other experiments—it wasthought that the motor control and strengthof animals that developed under conditionsof reduced gravity would be different fromthose of animals that developed on Earth. Asanimals learn to walk, the nervous system is

fine tuned to the conditions they experience. The fact that babies are born with very little motor control means that what they experience asthey gain particular motor skills may influence their development.

An animal from the Moon visiting Earth for the first time would feelvery heavy and would find it hard to move.This is because posturalmuscles needed to support its body against the force of gravity wouldbe very weak. The circulatory system would also have problemsbecause it would be harder for the heart to pump blood up to thehead. The animal might feel faint.

SKILL BUILDING 1. What are the advantages and disadvantages of each source of information used in this activity? What is the accuracy of each source? For example, ask each student about jumping rope.

• Can your sister, brother, neighbor jump rope?• When did the parent of your subject say he/she could first

jump rope?• Do you remember when you could first jump rope?

How old was I?

Figure 35 Diagram of student observing development of another student.


Developmental and Cellular Neurobiology Student Activity Sheet: Learning Activity III

STUDENT ACTIVITY SHEETObserving Your Own Development

Name ________________________________________________ Date __________________

1. What are your “vital statistics”?

______ weight ______ number of siblings______ height ______ position in family (what number child?)______ weight and length at birth ______ twin______ gender

2. At what age could you do the following?

Movement

______ lift head ______ sit up with support______ hold head up and look around ______ sit up without support______ support body with arms ______ reach and pick up a toy______ roll over ______ crawl______ grab something, hold onto it ______ crawl up stairs

Awareness of Self and Others

______ follow family members with eyes ______ recognize own name______ smile ______ point at things______ laugh ______ wave good-bye______ recognize self in mirror ______ copy sounds______ recognize hands ______ say first words______ recognize feet

Walking______ stand up from sitting or crawling position ______ jump on one foot______ stand without falling, if holding onto something ______ hop______ stand alone ______ skip______ walk while holding onto something ______ jump______ walk alone ______ run______ stand on one foot ______ walk up stairs

Skilled Movement______ eat with a spoon ______ throw a ball straight ______ catch a ball (if so,______ drink from a cup ______ draw a straight line what size ball?)______ drink from a glass ______ make a circle around a drawing of a house______ use a knife and fork ______ copy a circle, triangle or drawing of a house

3. How many different kinds of controlled movements could you make? ____________Add from above.

(from birth to age six)


VestibularFunction


GRADES 5–12

Section II



Vestibular Function Introduction

Vestibular FunctionTOPIC How will the body maintain a sense of balance in space?

The vestibular system is the part of the nervous system that controls balance.

INTRODUCTION The human body has a remarkable system for maintaining a sense of ori-entation and equilibrium. Human beings can keep their balance whilewalking on a tight rope (Figure 36) 100 feet above the ground, doingrepeated pirouettes in a ballet performance, and dodging in and out oftraffic on a busy street. How does the body calculate and control its move-ment so precisely?

Balance and equilibrium involve constant interpre-tation by the brain of sensory information comingfrom all over the body.This information includesvisual cues, touch sensations, and signals from theinner ear. Normal movements and stimuli encoun-tered in the every day environment do not upsetour equilibrium. However, we all have experienceddizziness and difficulty walking after spinningaround in a circle. What causes this disorientation,and how does the body return to equilibrium?Astronauts experience similar sensations of dizzi-ness and disorientation during their first few daysin the weightless environment of space. Upon

returning to Earth’s gravity, they must re-adapt and frequently have diffi-culty standing upright, stabilizing their gaze, walking, and turning cor-ners. How do different environmental conditions and stimuli affect astro-nauts’ orientation, movement, and equilibrium? The Neurolab team stud-ied these issues to gain a better understanding of the intricate functions ofthe human balance and sensory systems.

Things to Know

THE One of the most important components in the control of balance is the VESTIBULAR vestibular system. Part of the neuro-sensory system (“neuro” refers to SYSTEM nerves, “sensory” to the senses), the vestibular system processes informa-

tion about motion (acceleration, movement, and orientation) and helpsthe body to maintain or restore equilibrium.This system is key to oursenses of balance and self-motion and to our ability to distinguishbetween motion of the body itself and motion of things outside the body.

Figure 36 Diagram of student maintaining balance while walking a tightrope.



The vestibular system (Figure 37)is comprised of three semicircularcanals, two membranous sacscalled otolith organs in the innerear, and areas of the brain thatprocess information from theseorgans. Within the inner ear, thethree semicircular canals areshaped like inner tubes of tires.They contain fluid and hair cells.Hair cells have a small organ calledthe “hair bundler,” which isformed by dozens of small hairs.These small hairs extend into the

semicircular canals. When the fluid in the canals shifts or moves, the haircells also bend and signal the brain about the direction in which they arebeing moved.The brain uses this information to determine the directionand speed in which the body is accelerating or decelerating.

The semicircular canals help the body maintain balance and equilibriumand are oriented along three axes. Semicircular canals also help us tomaintain our fixed gaze, even in the presence of complex body move-ments (Figure 38A). One canal is horizontal. Its hair cells are maximallybent when the head is turned in the yaw axis (shaking from side-to-sideto communicate “no”) (Figure 38B). Another canal is perpendicular tothe horizontal axis. It is oriented like the wheels of a bicycle headedstraight. The hair cells in this vestibule respond maximally to pitchingmotions of the head (when the head moves up and down to communi-cate “yes”) (Figure 38C). The third canal is perpendicular to both of theothers, and its hair cells are bent most when the head rolls from one sidein a “maybe” shrug (Figure 38D).

Figure 37 Diagram of the vestibular system.

Figure 38B Diagram of yaw axis movement.

Figure 38A Diagram ofno movement.

Figure 38C Diagram of pitching motion.

Figure 38D Diagram of rolling motion.

Figure 38 Diagram of how the semicircular canals help the body maintain balance and equilibrium.

A B C D

Semicircularcanals

Otolith organs




Within the otoliths, the hair cells are stuckinto a gelatine-like membrane called theotolithic membrane. When the bodymoves, the otolithic sac moves with it.However, because the otolithic membraneis loaded with rocks (otoliths), inertiacauses it to lag (Figure 39).This lag causesthe hairs to bend, stimulating the haircells. When the head tilts, the sac also tiltsand the weight of the rocks causes the hairsto bend.This way the otolith sack detects linear motion and tilt.

In addition to the vestibular system, theeyes also play an important role in balance.

Visual signals that are sent to the brain provide information about bodyposition and motion relative to one’s surroundings.These signals work inconcert with those from the vestibular, tactile (touch), and motor (mus-cles, joints) systems to tell the brain what is happening.The eyes alsoautomatically move in a direction opposite of the head to maintain a sta-ble visual image.This coordination of eye and head movement is calledthe vestibular-ocular reflex and can take various forms. For example, onetype of vestibular-ocular reflex, known as nystagmus, occurs when a per-son is spun around and then suddenly stops.The eyes respond by movingin the direction opposite to the direction of spin in an attempt to stabilizethe field of vision until equilibrium is restored.

MOTION AND The perception of our body’s position, known as proprioception, is PERCEPTION determined through sensors in our joints, skin, and muscles. These sen-

sors detect touch, pressure, movement, and the contraction of muscles.The input from these sensors allows us to determine, or establish, theexact position of most parts of our body and coordinate our movements.

The coriolis effect occurs when the head is in motion and constantlychanging direction. For example, coriolis effects occur when one is on aboat that is rocking and rolling, or is in an airplane experiencing turbu-lence, or in a car with soft suspension going around a lot of curves. Inthese situations, acceleration information is bombarding each of the semi-circular canals at the same time.The vestibular organs make connectionswith many centers, such as the cerebellum (to coordinate motion), and tothe eyes (to coordinate head-eye movements).The vestibular organs alsomake connections with the hypothalamus, which controls many auto-nomic functions.This connection is responsible for nausea and dizzinesswhen the vestibular system is over-stimulated.

Figure 39 Diagram of a hair cell.

Otolithic membranelags because of inertia


Vestibular Function Learning Activity I

Vection is the illusion that the body is moving in a cir-cle (circular vection) or in a line (linear vection)when, in fact, external visual cues are moving relativeto the body. For example, vection occurs while we aresitting in a parked car, reading, or looking ahead. Wesometimes “feel” as though the car is rolling, when, inreality, the vehicle next to the car has started moving(Figure 40).Visual cues, especially those located in theperiphery of one’s vision (things a person can see outof the corner of his or her eye) strongly affect sense ofmovement, even without any sensations in the innerear vestibular system, and without any actual movementof the body.

LEARNING ACTIVITY I:Visualizing How the Vestibular System Works

OVERVIEW In this activity, students will learn about theeffects of different types of motion on thehairs suspended in fluid in the inner ear.

SCIENCE & Observing, collecting and recording MATHEMATICS quantitative data, measuring angles of SKILLS rotation, calculating averages, creating

charts, creating models, drawing conclusions

PREPARATION 15 minutes (at least one day before the TIME activity)


MATERIALS Each group of 3 – 4 students will need:

• One tube of super glue (should bewater resistant and adhere to glass and hair-like fibers) OR a hot glue gun and glue sticks

• Automatic turntable (such as for pottery class), centrifuge, or other rotating device (such as a Lazy Susan orold record player)

MAJOR CONCEPTS

• Hair cells within thevestibular system areaffected by movementof the head in differentdirections.

• Movement causes fluidin the inner ear to shift,bending the hairsattached to the hair cells.

• Hair cells send messagesto the brain indicatingthe direction of move-ment.

• Hair cells specifically aresensitive to changes inthe speed or direction ofmotion.

B

A

Figure 40 Diagram of vection.




MATERIALS (cont.) • Set of false eyelashes or strands of another fuzzy or wispy material

• Clear glass jar or cylinder with lid• Water• Watch• Note pad• Pen or pencil

BACKGROUND In this activity, students create a model that permits them to visualize themovement of fluid and bending of hairs in the inner ear in response tomotion. It also demonstrates how the vestibular system maintains orrestores equilibrium despite movement.

The vestibular system is key to our senses of balance and self-motion.

Located in the inner ear, the vestibular apparatus is comprised of threecanals containing fluid and receptor cells, called hair cells. Long hairsextend from the hair cells into the canals and are embedded in the cupula.Motion of the head causes the fluid in the canals to shift or move, whichin turn, causes the hairs to bend.The direction of the movement deter-mines the direction in which the hairs are bent. When motion ceases, thevestibular system reacts in the opposite direction until equilibrium isreached again and the hairs are motionless.

In this activity, students will observe the importance of acceleration anddeceleration in producing movement of hairs suspended in fluid. Studentswill be able to see how water within a rotating cylinder first accelerates,and then decelerates, as the movement stops. Because the speed is con-stantly changing during this movement, hairs within the cylinder will bebent to different degrees. While accelerating, they bend more; whiledecelerating, they straighten. If rotation continues at a constant speed in aconstant direction, the hairs remain in a stable unbent position.

In this exercise, students can observe and compare how the “hairs” moveas a container of fluid is rotated in different directions, with accelerationand deceleration, and at a constant speed.These observations can then becompared to the way in which the vestibular organs respond to differenttypes of head movements. Students can measure and compare theamount of time it takes to restore equilibrium with different degrees ofmotion and acceleration.



PROCEDURE 1. At least one day before actually performing the activity, glue (or have the students glue) the false eyelashes or strands of other fuzzy material to the inside of the beakers, jars or glass cylinders. Attach to the side of the cylinder (not the bottom).

2. Organize students into pairs or groups of 3 – 4, depending on theamount of materials available.

3. Have one student from each group fill the cylinder with water. Let the water settle until it is motionless.

4. Direct the students to rotate the cylinder quickly 90 degrees to the right (maintaining the vertical position of the cylinder) and observe what happens to the hairs on the eyelashes (Figure 41B).

5. Have the students rotate the cylinder 90 degrees in the other direction and record observations.

6. After the motion stops, have students quickly rotate the cylinder 180 degrees to the right, this time using a watch to measure the amount of time required for the hairs to return to the straight position.Have students record the time (Figure 41D).

7. Direct the students to repeat this procedure, with each student taking a turn rotating the cylinder, observing the watch, and recording the time. Have them record the name of the person who rotated the cylinder and the person who observed the watch beside the measured time.

8. Have the students calculate the average time required for the hairs to come to rest after rotating the cylinder, and to record their calculations.

9. Have students quickly rotate the cylinder 90 degrees to the right andthen immediately rotate 180 degrees to the left, measuring the timerequired for the hairs to stop moving. Have them record their observa-tions.

Figure 41 Diagram of furry or wispy material or false eyelash in motion.

Figure 41A at rest. Figure 41B 90˚rotation. Figure 41C motionless. Figure 41D 180˚rotation.

A B C D




10. Have students present their data from steps 7, 8 and9 in tabular format (Figure 43).

11. If a rotating device or turntable is available, have stu-dents place the cylinder on the device and rotateslowly (so as not to splash or dislodge the eyelashes)at an even rate for one minute (Figure 42). Havethem time one minute using the watch. Ask the stu-dents to observe what happens to the hairs as theycontinue to spin, and after rotation is stopped. Havethem record their observations.

EVALUATION At this point, students should understand how rotation of varying direc-tion and magnitude affects the motion of hairs suspended in fluid.

REVIEW 1. How did the direction of rotation affect the direction in which the QUESTIONS hairs bent?

The hairs bent in the opposite direction of the rotation.

2. Was there a difference in the time required for the hairs to stop moving after the 90 degree and 180 degree rotations? How do you explain this?Students’ answers will vary. There should be no difference in the time because both stops were sudden and the movement was not continuous.

3. What happened to the hairs when the rotation was continuous for one minute? What happened to the hairs when the rotation suddenlystopped? What do you think happens to our vestibular system whenwe spin continuously for a period of time? What happens when we stop suddenly?The water and hair cells moved together which allowed the hair cells to straighten out when the motion was constant for one minute. When

Understanding the Vestibular System

Figure 43 Example of chart to record motion observations.

90 degrees 180 degrees 90/180 degrees 1 minute rotation Person Person (observations) (time) (time) (observations) rotating w/stopwatch

Figure 42 Diagram of students observing fuzzy material in action.



the hairs suddenly stopped, the water caused them to move forward.The hair cells move in the direction of the spinning. When suddenly stopped, we fall forward and if we try to stand up we experience dizziness.

THINKING 1. In step 7, each student took a turn at each task. Were the times CRITICALLY measured the same or different for each student? What might

account for the differences in time?

2. If the water in the cylinders was replaced with another substance that was more dense, such as liquid detergent, or less dense, such as air, how would the movement of the hairs change? What if the hairs were in a vacuum? What other factors might affectmovement? If the hairs were placed in a dense liquid, the movement would be slower and not as obvious. If they were placed in a less dense sub-stance, movement would be faster and more obvious. If they were placed in a vacuum, there would be no movement of the hairs.

3. Why do patients who are bed-ridden for long periods of time often experience dizziness and difficulty standing upright?These patients experience dizziness because their vestibular systems have not been required to function. Due to the lack of movement, whenthe patients stand, the vestibular systems are activated and their bodies have to adjust.

SKILL BUILDING Have students pool their measurements from the different trials and calculate class averages. How much did the individual measure-ments vary from the class averages? What does this tell us aboutincorporating several trials into the design of an experiment?



Figure 44A at rest. Figure 44B 90˚rotation. Figure 44C motionless. Figure 44D 180˚rotation.

Vestibular Function Student Activity Sheet: Learning Activity I

STUDENT ACTIVITY SHEETVisualizing How the Vestibular System Works

Name ________________________________________________ Date __________________

OBJECTIVE To learn about the effects of different types of motion on the hairssuspended in fluid in the inner ear.

MATERIALS • Tube of super glue• Rotating device• Fuzzy or wispy material• Clear glass jar or cylinder with lid• Water• Watch• Note pad• Pen or pencil

DIRECTIONS Work in groups of four, maximum.Your group will need all ofthe materials.

PROCEDURES 1. At least one day before actually performing the activity, glue the fuzzy material to the inside of the beaker or glass cylinder. Attach the fuzzy material to the side of the beaker or cylinder (not the bottom).

2. Have one member from your group fill the cylinder with water.The water should settle until it is motionless.

3. Rotate the cylinder quickly 90 degrees to the right (maintaining the vertical position of the cylinder) and observe what happens to the fuzzy material (Figure 44B).

A B C D



Page 2

Name ________________________________________________ Date __________________

4. Rotate the cylinder 90 degrees in the other direction and recordobservations.

5. After the motion stops, quickly rotate the cylinder 180 degrees to the right, this time using a watch to measure the amount of time required for the hairs to return to the straight position (Figure 44D).Record the time.

6. Repeat the procedures, with each student in your group taking a turn rotating the cylinder, observing the watch, and recording the time.Using the chart, record the name of the person who rotated the cylin-der and the person who operated the watch beside the measured time.

7. Calculate the average time required for the hairs to come to rest after rotating the cylinder, and record your calculations.

8. Quickly rotate the cylinder 90 degrees to the right and thenimmediately rotate 180 degrees to the left, measuring the timerequired for the hairs to stop moving. Record your observations.

9. Present your data from steps 6, 7, and 8 in tabular format (Figure 45).

10. If a rotating device is available, place the cylinder on the device and rotate slowly (do not splash or dislodge the fuzzy material) at an even rate for one minute. (Use the watch to time one minute.) Observe what happens to the hairs as they continue to spin, and after rotation is stopped. Record your observations.


Figure 45 Example of chart to record motion observations.

90 degrees 180 degrees 90/180 degrees 1 minute rotation Person Person (observations) (time) (time) (observations) rotating w/watch



Page 3

Name ________________________________________________ Date __________________



90 degrees 180 degrees 90/180 degrees 1 minute rotating Person Person (observations) (time) (time) (observations) rotating w/watch


Vestibular Function Learning Activity II

LEARNING ACTIVITY II:Vestibular-Ocular Reflex

OVERVIEW In this activity, students will perform variousinvestigations to understand the vestibular-ocular reflex and learn about the importance of visual cues in maintaining balance.

SCIENCE & Observing, communicating, collecting quantita-MATHEMATICS tive data, calculating frequencies, drawing SKILLS conclusions.



MATERIALS For IIA of the activity, each pair or group of students will need the following items:

• Pen or pencil• Note pad• Book

IIB of the activity will require the following:

• Chair that rotates smoothly—preferably with back and arms, such as a desk chair

• Watch or clock with second hand• Note pad• One blindfold (optional)• Protractor• Chalk• String or yarn (3 feet)• Push pin• Yard stick for drawing lines• Pen or pencil

MAJOR CONCEPTS

• The vestibular system helps tomaintain balanceand equilibrium.

• Vestibular-ocularreflexes coordinateeye movement relative to headmovement.

• The nystagmus(one type ofvestibular-ocularreflex) helps theeye to stabilize thefield of visionafter movement.The eyes usuallymove in the direc-tion opposite theinitial movement.




BACKGROUND This lesson is similar to some of the exercises the Neurolab team conduct-ed as they studied the vestibular function in space. It helps to demonstratethe importance of gravity and visual cues to the human balance and sen-sory systems. Gravity provides a continual downward force, which thevestibular system (particularly the otolith organs) uses to process infor-mation about motion and orientation.To understand the effects of spacetravel on the vestibular system, Neurolab scientists studied how thevestibular system reacts to certain stimuli, within Earth’s gravitational fieldand under microgravity conditions.

The following activities will demonstrate the vestibular-ocular reflex,which is the body’s way of coordinating signals from the visual field withsignals from the vestibular organs of the inner ear. This reflex is extremelyimportant for stabilizing vision when we are moving. When the headrotates or tilts in any direction, the eyes move in the opposite direction tocompensate, maintaining a stable visual image.Therefore, movements ofthe eyes can provide clues about what is happening in the vestibular sys-tem.The eyes respond similarly to movement of objects outside the body.However, the vestibular-ocular reflex occurs only when the vestibular sys-tem is stimulated (in other words, when the head moves).

During these activities, students will observe eye movements and monitorthe stability of the visual field during different types of movements:saccadic, the fast movement of the eye and smooth pursuit, the slowmovement of the eye during the vestibular-occular reflex. In IIA, studentswill compare stability of a moving image under two conditions:(1) when the object of vision is moving but the head is stationary; and(2) when the head is moving but the object is stationary. When the headis stationary, the vestibular system is not activated, and the image blursmore quickly. When the head is moving, the vestibular system is stimulat-ed and works together with visual and proprioceptive sensory systems tomaintain a stable image.

In IIB, students will compare the effects of rotation on the sensation ofspinning under varying conditions: (1) when the visual system is activated;(2) when the visual system is not activated; and (3) when the otolithorgans are activated by a downward movement.

PROCEDURE IIA: Stability of Moving Images

1. Assign each student a partner.

2. Have the partners stand about five feet away from each other. One student will be the subject, the other will be the recorder.



3. Tell the subject to look at his or herpartner, and then to look away to abook placed about three feet away.Therecorder should look at the subject’seyes and determine the type of eyemovement he or she is exhibiting.Therecorder should record the type of eyemovement, saccadic or smooth pursuit.

4. Have the students reverse roles andrepeat steps one through three.

5. Next, have each subject focus on theend of a pen or pencil held by therecorder about one foot in front of thesubject’s face.Tell the subject to holdhis or her head still while the recorder

moves the pen or pencil back and forth slowly in front of the subject’seyes. Instruct the recorder to move the pen or pencil from one side tothe other as though he or she were trying to hypnotize the subject (Figure 47A).

6. Each partner should record the types of eye movement that are exhibited by the other: saccadic or smooth pursuit.

7. Let the team members switch roles and repeat the exercise.

8. Finally, have one student from each team hold a pen or pencil about a foot in front of his or her partner’s face while the partner keeps his or her eyes on the pen or pencil. Both of the students should move their heads around while observing (Figure 47B).

9. Have the students record their observations of each other’s eye movements.

10. Discuss these observations with the students. Ask if the eye movements were the same in each trial. Have students compare and contrast their observations.

Figure 47A Diagram of techniques for testing saccadic (fast eye movement).

1 foot

Figure 47B Diagram of techniques for testing smooth pursuit (slow eye movement).

1 foot

Figure 46 Diagram of student observing saccadic eye movement.

3 feet

5 feet



IIB: Effects of Rotation on Vision

1. Instruct students to draw a circle on the floor by attaching athree-foot string to a piece of chalk and attach the other end toa push pin. Have the students establish a dividing line by draw-ing a line through the center of the circle.They should thenalign the center point of the protractor with the center of thedividing line of the circle. Direct the students to place a markoutside of the circle at the dividing line (0˚).They shouldplace another mark outside of the circle at 120.̊ The studentsshould make sure that the marks are visible to the person rotat-ing the chair (Figure 48).

2. Select one rotating chair with arms for this activity and place the chair at the center of the circle. Since students will be spin-ning in the chair, caution them to exercise care. Students sitting in the chair should hold the arms of the chair during the rotation.

3. Before beginning, demonstrate to students how to turn the chair care-fully, so that the student sitting in the chair does not tumble out. Ifnecessary, review the procedure with the students to make sure thatthey understand what they are supposed to do.

4. Have students conduct the activity in groups. One student will be thesubject, a second student will spin the chair and the remaining stu-dents will be recorders and time keepers.

5. Have each subject sit erect in a rotat-ing chair. Another team membershould turn the student in the chairfor a full minute at 120 degrees persecond, then suddenly bring the stu-dent to a full stop (Figure 49).

6. The other members of the teamshould observe the eyes of the studentsitting in the chair after it has beenstopped. Using the watch, they shouldtime how long it takes for the effectof spinning on the student’s eyes tostop and record their observations.


Figure 49 Diagram of student rotating student 120 degrees per second.

DividingLineCenter Point

Protractor

Figure 48 Diagram of 120 degree floor drawing.



7. Have the students repeat step 3, butinstruct the student in the chair to holdhis or her head forward during spin-ning.The other partners should observehow long this student’s eye movementlasts after the chair has stopped and thenrecord these observations (Figure 50).

8. Have students within the groups switchroles so that they all will have an oppor-tunity to participate in the various rolesof this activity.

9. Have the students in each group sum-marize their data and present a groupaverage of time required to stabilize eyemovement after the spinning, both instep 3 and step 5.

EvaluationREVIEWQUESTIONS 1. What does the vestibular-ocular reflex do?

The vestibular-ocular reflex coordinates eye movement relative to head movement.

2. What does the vestibular system do?The vestibular system helps the body to maintain balance. It helps the body to determine the difference between motion of the body and motion of things in the world.

3. What is the difference between “saccadic” and “smooth pursuit”? There are two components of eye movement during the vestibular-ocular reflex.The fast movement of the eye is called “saccadic” and the slower movement is called “smooth pursuit.”

4. Why is the vestibular system important to movement?It helps the body to maintain balance and to adjust to movements of the body as well as movements outside of the body.

5. What is motion sickness?The symptoms of dizziness, drowsiness, and nausea that are caused by the coriolis effect or pseudo-coriolis effect.

Figure 50 Diagram of student rotating student120 degrees per second while head is in pitched position.



Learning Activity IIVestibular Function

THINKING 1. Why do people who have problems with their vestibular systems CRITICALLY suffer from motion sickness?

If the vestibular system is damaged, the signals going to the brain are inappropriate or missing, causing motion sickness.

2. How is motion sickness related to visual cues?The symptoms of motion sickness may be triggered by visual stimuli.The pseudo-coriolis effect is inducted by visual illusions of self-motion.

3. What would happen if the vestibular system were destroyed? Explain how one would act and feel.A person would have problems adjusting to movement and maintaining balance.The person may experience some motion sickness.

4. Why might a person experience motion sickness when not moving or in an IMAX theater?The visual illusions would overload the vestibular system producing the pseudo-coriolis effect.

5. Will the vestibular system adapt to microgravity? Without gravity togive us a constant downward reference, how will the roles of visual and touch cues change?The vestibular system would respond and adapt to microgravity. With-out gravity, the vestibular system would have to make adjustments to the constant movement of the body just as it does when astronauts are in space.

SKILL BUILDING Have students use the Internet tolocate resources related to disorders ofthe vestibular system (Figure 51).How might Neurolab research pro-vide insight into these disorders?

Figure 51 Diagram of student using the Internet.


Vestibular Function Student Activity Sheet: Learning Activity II (IIA)

STUDENT ACTIVITY SHEETIIA. Stability of Moving Images

Name ________________________________________________ Date __________________

Head Position Description of eye movement Subject Recorder(stationary or side-to-side) (smooth or saccadic)



STUDENT ACTIVITY SHEETIIB. Effects of Rotation on Vision

Name ________________________________________________ Date __________________

Head Position Description Length of time for Person in chair Person spinningof eye movement eyes to stop moving (subject) (observer)

Vestibular Function Student Activity Sheet: Learning Activity 2 (IIB)


SpatialOrientation andVisuo-motorPerformance


GRADES 5–12

Section III



Spatial Orientation and Visuo-motor Performance Introduction

Spatial Orientation andVisuo-motor PerformanceTOPIC Gravity is an important component that enables organisms to establish

frames of reference and maintain a sense of orientation with respect toobjects in the environment.

How did the Neurolab astronauts maintain their sense of spatial orien-tation in a microgravity environment?

INTRODUCTION Perception of where one is located with respect to certain landmarks inthe environment (self-orientation), and where specific objects are locat-ed with respect to each other (object-orientation), are interdependent.Our abilities to recognize and interact with objects in the environmentdepend on proper perception of self-orientation as well as object-orientation.

Our perception of self-orientation depends on input from our externalsensory organs (exteroceptors), such as our eyes, ears, and nose. It alsodepends on input from our internal sensory systems (interoceptors).These include proprioception, which is a system of specialized receptorsand nerves in our bodies that monitor the positions of our muscles andjoints. Another example is the vestibular system located inside the headnear each ear.This system responds to rotations and accelerations of thehead as well as to gravity. Under ordinary conditions, the input to thebrain from all of these sensory systems are consistent with one another.However, in microgravity conditions, the vestibular information that thebrain receives changes, and this sometimes leads to motion sickness, aswell as to illusory perceptions.

Things to Know

RELATIVE The term frame of reference refers to a coordinated system for specifying POSITION AND the locations and movements of objects. For example, map makers use the PATH ANALYSIS North and South poles, and the equator, to establish a frame of reference

for the Earth.This allows us to specify locations in terms of their latitudeand longitude.

Similarly, the brain uses its sensory organs to establish and maintain aframe of reference to specify locations of objects with respect to the body.



For example, in the Northern Hemisphere, vision can be used to establish“East,” the direction from which the sun is seen to rise in the morning,and “West,” the direction where the sun sets in the evening. Locations andmovements of the body and other objects can then be specified withinthis frame of reference. For example, one may think, “To go home, I musttravel eastward.”

Vision can also potentially provide a frame of reference for “up.” Forexample, we know that to see the sky we look “up,” or that to determinethe direction of the ground on which our feet rest we look “down.”Information about “up” and “down” is also provided independently bythe otolith organs, a component of the vestibular system that respondsdirectly to gravity.

NAVIGATION When you travel from a location in the environment to which you laterwant to return, your brain is confronted with the problem of how to navi-gate back home. One way your brain might accomplish this task is to usesome form of Path lntegration.This is an automatic process performed by

the brain to try to continuously keep trackof how far you have traveled, and in whatdirection, over each segment of your path,and then use this information to computeyour current position relative to yourstarting point. Many animal species, eventhose with very simple nervous systems,are able to utilize some form of path inte-gration to navigate. For example, ants cannavigate their way back home after forag-ing in search of food (Figure 52).

Our brains are able to construct and storespatial maps that specify our current loca-tion with respect to important landmarks.

These maps are formed by combining information from interoceptors withcorollary discharge. A corollary discharge is a copy of the motor com-mands that the brain sends to the muscles. For example, if the brain is try-ing to figure out how far the body has walked since leaving home, it hastwo obvious sources of information. One is to examine the corollary dis-charge of the signals that were sent to the leg muscles. In other words, thebrain knows how many steps you have walked because it was the brainitself that sent the commands to the leg muscles that caused you to walk.

An independent source of this same information comes from propriocep-tion which supplies the brain with detailed information about positionsand movements of the muscles and joints in the legs. Similarly, the

Figure 52 Diagram of path integration.

Tree

Home path

Ant hill

Outgoing path




vestibular system sends information to the brain every time you accelerateor decelerate in speed, or rotate to turn a corner.

Finally, this information about your current location is augmented byvision, olfaction, and audition. For example, through vision, you can tellthat you are in your classroom by looking around, through olfaction, youcan tell that you are near the cafeteria by the way it smells, and throughaudition, you can know that you are near your classroom because youcan hear the sound of your students talking.

Under ordinary circumstances, the information supplied to the brain fromthese various sources is consistent and thus the spatial maps that areformed by the brain are accurate. In mammals, there is a specialized struc-

ture called the hippocampus that appears to play amajor role in storing these maps (Figure 53). The hip-pocampus is a seahorse-shaped structure located deepin each hemisphere of the brain. Self-orientation iscoded in the hippocampus in the neural firing patternsof specialized neurons called place cells.These placecells buzz with electrical activity whenever an animalknows it is located in a certain place. Different placecells are active in different locations. By recording theactivity from many place cells at the same time, scien-tists essentially can read an animal's mind and tellwhere the animal thinks it is located.

SPATIAL In microgravity conditions, the vestibular information that the brain ORIENTATION IN receives is changed. In order to understand why this is so, we MICROGRAVITY need to understand how the vestibular system operates. The vestibular sys-

tem is composed of two subsystems called the semicircular canals andthe otolith organs. There are three semicircular canals and they signal tothe brain whenever the head is rotated. One responds to yaw motions(motion that occurs when you shake your head side-to-side), a second topitch motions (motion that occurs when you do a back flip), and a thirdto roll motions (motion that occurs when you turn cartwheels).Theotolith organs send two kinds of information to the brain. First, they sig-nal whenever you accelerate or decelerate (the feeling of being suckedinto the back of the car seat when you press on the gas pedal to passanother car). Second, they respond to gravity to tell you which end ofyour body is “up,” and which is “down.”

Figure 53 Diagram of the hippocampus within the brain.


Imagine that you are performing a cartwheel to your left. As you first startthe motion, your semicircular canal signals that your head is starting torotate to the left, and simultaneously your otolith organs are signaling thatthe “up” direction is shifting from the top of your head towards yourright ear. Halfway into the cartwheel, your semicircular canal continues tosignal that your head is rotating to the left, and now your otolith organssignal that the top of your head is in the “down” position. If you haveyour eyes open, the input to your brain will be consistent with the inputfrom your vestibular system because the world will look “upside-down.”

Similarly, the proprioceptive inputs from your muscles will indicate thatthe force from the floor shifted from your feet to your hands. If you wereto turn the same cartwheel under the condition of microgravity, the inputfrom your semicircular canals and from vision would be identical, but theinput from the otolith organs would be inconsistent because it would notsignal that the direction “up” shifted during your cartwheel. Also theforce exhibited by the floor on your muscles would be less in microgravity.

This kind of inconsistent input is a regular occurrence inthe brains of astronauts during a space flight. Astronautsexperience the spacecraft and Earth from their bodilyattitudes. Because the “down cue” that Earth’s gravityprovides to the otolith organs, as well as to the proprio-ceptive receptors in the muscles and joints are not pre-sent in microgravity, the crew must rely on vision tobecome oriented and figure out where they are locatedin relation to the space they occupy. In daily life onEarth, the “floor” is always beneath our feet and peopleare upright. However, in weightlessness, free floatingcrews view the cabin interior, and each other, from manyorientations. For example, when floating in symmetricalcabin interiors, the surface beneath their feet feels like“the floor,” even if they are floating upside-down withtheir feet touching the ceiling (Figure 54). As a result,

space flight often causes altered spatial orientation, illusions of body orien-tation, changes in visuo-motor performance, and space motion sickness.

TRICK MAZE One Neurolab animal experiment tried to determine whether or not EXPERIMENTS spatial maps in the hippocampus are disrupted by the inconsistent infor-ON NEUROLAB mation provided to the brain under conditions of microgravity. Neurolab

scientists used a unique set of trick mazes designed to fool the animalsinto thinking they were in one place, based on corollary discharge andproprioception (where the animals thought their legs should have takenthem), when in reality they were in another place (which they were able


Figure 54 Diagram of free floating.




to see from what their eyes told them). One mazewas called the Escher Staircase (Figure 55) and anoth-er was called the Magic Carpet (Figure 56). Scientistswanted to see whether the animals’ hippocampi weretelling them they were “'home” or not by measuringthe activity of the place cells in the hippocampi.

In the Escher Staircase, there was a route aroundthree inner walls of a corner of a cube. In the pres-ence of gravity, you could not walk around the stair-case because you cannot walk along the sides ofwalls. However, in the absence of gravity’s effect, itwas possible to follow a route that combined three 90degree “yaw” turns with three 90 degree “pitches”and end up back home at the starting point. The ani-mal did not have any input from its otolith organs

informing it that it had been walking on the wall instead of the floor dur-ing part of the route. It had been predicted that even though the animalwas back to where it started, it would be confused.The visual systemwould tell the brain that all the visual landmark cues indicated that theanimal was back where it started the maze, but the path analysis per-formed by the brain would probably think the animal needed to turn onemore corner to return home (as would be the case if the animal had notbeen able to walk on the walls).

The Magic Carpet maze played a similar trick that was possible only inthe absence of gravity’s effect. It was a plus-shaped maze that could pitchand roll the animal so they ended up facing 180 degrees in the oppositedirection to where it had started without ever turning around. Again, thevisual cues told the animal it had turned around, but path analysis wouldnot. It was believed that the hippocampal place cells would put moreemphasis on path analysis computations than on visual information.Thus,the prediction was that when the animal returned to its starting position,the hippocampus would underestimate the animal’s true position by 90degrees on the Escher Staircase and by 180 degrees on the Magic Carpet.

Figure 55 Diagram of an Escher Staircase.

Figure 56 Diagram of the Magic Carpet.

56A In hand 56B After roll 56D Starting positionA B C D

56C After roll and pitch


Spatial Orientation and Visuo-motor Performance Learning Activity I

LEARNING ACTIVITY I:Finding Your Way Around

Without Visual or Sound Cues

OVERVIEW In this activity, students will play a series ofsimple games to investigate navigation withoutvisual and sound cues.

SCIENCE & Observing, collecting quantitative data, creatingMATHEMATICS graphs, interpreting data, drawing conclusions,SKILLS communicating



MATERIALS • Access to an open area• Measuring tape• Timer (watch or clock with second hand)• Graph paper, one sheet per student• Pencil (pen or chalk is acceptable),

one per student• Bell• Blindfold, one per student• Candy to reward for foraging• Statistical calculator

BACKGROUND The brain is able to interpret information fromseveral different body systems to estimate posi-tion.Visual cues, information from the otolithorgans in the inner ear, sound cues, and information from the motor sys-tem are used to determine spatial orientation.

This activity allows students to investigate how well the central nervous system is able to estimate position based on information other than visual and sound cues.

MAJOR CONCEPTS

• The brain com-bines informationfrom several differ-ent sources to esti-mate position.

• Inertial navigation(navigation basedon motion-relatedcues) can providedirection withoutvisual or auditorycues.

• The environmentcan be navigatedwith some successby solely usingfeedback receivedby the brain fromself-motion sen-sors in the body.




PROCEDURE 1 Navigating Without Visual or Sound Cues

1. Have each student take a partner and a blindfold to an open area.

2. Designate an area as “home” base by placing a piece of paper on the ground where the students are, or mark the spot with tape forming an “X” on the ground or on the floor.

3. Have one member (subject) of each student team tie the blindfold over his/her eyes so he/she cannot see anything.This is a test to see if the student can navigate without visual cues. Encourage the students not to cheat.

4. Once blindfolded, each subject should walk around continuously for 30 seconds, like an ant foraging for food, and then try to return to the same spot where he/she started (Figure 57). Have the students make at least four turns as part of the path.They may go anywhere, as long as they try to end up at the starting place after 30 seconds. Each student’s partner should let him/her know how much time has elapsedevery 10 seconds. Have the partners move around so that the subjects cannot use the sound of their partners’ voices as the cues for “home.”

5. Make sure that the partners do not give the blindfolded students any hints. The environment should be as quiet as possible so that students receive no sound cues. Once each blindfolded student believes he/she has returned to home base (or, after the 30 second time limit is

Figure 57 Diagram of student walking blindfolded to show how inertial navigation can provide direction without sight or sound.

BlindfoldPosition chart

Home path

Subject

AssistantStart

End distanceEnd


reached), instruct him/her to remove the blindfold and measure how far he/she is from the starting mark.This distance should be recorded.Instruct the students not to worry if they end up far away from “home”after their first try.

6. To add excitement, distribute little packets of candy at random and have the students forage on hands and knees blindfolded, starting from a location called home, marking the floor (or pavement, if you are outdoors) with something they cannot feel, such as chalk.Then ring a bell and have them try to get back to home base within five seconds.The students might pretend that they are foraging ants and that the bell is a danger signal. Thus, they would try to get back “home” quickly.

Each student should have the opportunity to try this experiment at least once.

PROCEDURE 2 Using Quantitative Information to Assist Navigation Without Visual or Sound Cues

Note to Teacher: Encourage students not to make any audible clues that might alter results.The environment should be quiet.

1. Have your students repeat the previous activity, again blindfolded. But this time, instead of having the blindfolded students wander around randomly, have them count the number of steps they take in each direction.

2. The partner should help the blindfoldedstudent by writing down the numberand direction of steps taken by the blind-folded student. Partners can try to chartthe student’s course by drawing the stu-dent’s position at each step on a sheet of graph paper (Figure 58).

3. At 30 seconds, the blindfolded studentsshould try to find their way “home” by guessing where they are, using how far they have gone in each direction as acue. Direct each blindfolded student totell his/her partner how far, and in which


Figure 58 Diagram of a position chart.




direction(s) he/she thinks he/she needs to travel in order to reach home. (It is acceptable if the partner looks at the chart to see if the blindfolded student is correct, but the partner should not give any hints.)

4. The student should now try to find home. Once the blindfolded students reach the place they believe to be “home,” have their partners measure the distance from where the students ended to the actual starting place, or “home.” Have students compare their estimates of thedistance to home with the actual measurements. Each student should try the experiment.

PROCEDURE 3 Using a Pre-established Pattern to NavigateWithout Sound or Visual Cues

1. All students should be blindfolded for this exercise. As many students can participate at one time as available space will allow.

2. Students should blindfold themselves and try taking10 steps forward from their “home” mark.Theyshould then turn 90˚ to the right, take 10 moresteps, turn 90˚ to the right again, take 10 moresteps, and stop (Figure 59). Ask the students if theythink they are back to where they started yet.

3. Have the blindfolded students turn 90˚ to theright and take 10 more steps. Have the studentsadd all their 90 degree turns to determine howmany degrees they have rotated in total.

4. Ask the students where their brains tell them theyare. Direct them to lift their blindfolds and see ifthey are “home.”The students should measure howfar they are from their mark and record the mea-surement. If the students counted accurately, theyshould be close to the place where they started.

5. Have students compare measurements from the three trials. Have them identify the trial in which they navigated most accurately and the trial in which they were least accurate in returning to home. Why do they think the results varied from one trial to another?

Figure 59 Diagram of a pre-established pattern.

Home(start here)

90˚

90˚ 90˚

32

41



EvaluationREVIEWQUESTIONS 1. What types of information does the brain use for navigation and

determining position?The brain receives and utilizes sensory information from the eyes, ear,and nose to determine position.

2. Is it possible to estimate position using information from only one or two sources?Yes. It is possible.

THINKING 1. What is the minimum amount of sensory information needed forCRITICALLY navigation?

A minimum of two sensory information is needed for navigation.

2. Was navigation successful without visual cues?

3. How much error occurred when using each of the tactics?

4. Which tactic produced the least error? Why?

5. How much more or less difficult would the task have been if one could walk up and down walls?

SKILL BUILDING 1. Have students pool the class data from each of the trials, compute the mean distance from “home” for each trial and, using a statistical calculator, find the standard deviations (averages) of each of the trials.Have them use this information to decide whether the results of each trial are different or not.

2. Have student teams devise their own experiments to further investigate navigation without visual cues.



Spatial Orientation and Visuo-motor Performance Student Activity Sheet: Learning Activity I

STUDENT ACTIVITY SHEETFinding Your Way Around

Without Visual or Sound Cues

Name ________________________________________________ Date __________________

Student Name Procedure 1 Procedure 2 Procedure 3

TotalAverage


Spatial Orientation and Visuo-motor Performance Learning Activity II

LEARNING ACTIVITY II:Pitch, Roll and Yaw: The Three Axes of Rotation

OVERVIEW This exercise will help students understand how the visual and vestibular systems workwith the hippocampus to determine locationand direction.

SCIENCE & Observing, measuring, visualizing objects in MATHEMATICS three dimensions, drawing conclusionsSKILLS



MATERIALS No materials needed

BACKGROUND The body is capable of rotating in three differ-ent ways (roll, pitch, and yaw).This activitywill help students understand the three axesof rotation.

Body in Rolling MotionThe sideways motion of a body doing a cartwheel (Figure 60) is called a roll.

Body and Head PitchingThe motions of the body when somersaulting (Figure 61) are called ahead over heels pitch. The head is up, then down, then up, then down.Throwing a football or a baseball is also a pitch motion.

YawWhen you stand up and turn left and right, the motion you have made iscalled a yaw axis motion (Figure 62). One “yaws” when spinning aroundin a rotating chair, or when doing a pirouette.

MAJOR CONCEPTS

• Without gravity’seffect as a reference,it is difficult to detectthe body’s orientation.

• In microgravity, astro-nauts’ brains will relyon place cells withinthe hippocampus forinformation aboutposition.

• Place cells are morestrongly influencedby computationsbased on path inte-gration than by visual cues.



Spatial Orientation and Visuo-motor Performance Learning Activity II

HEAD There are cells deep within the brain that tell the hippocampus in which DIRECTION direction the head is facing in the yaw axis.These are called head-directionCELLS cells. The head direction cells always specify direction relative to some

important landmark. In the classroom, the front of the classroom mightprovide a landmark to form a frame of reference labeled by the brain as“forward” (facing the front of the classroom) and “backward” (facing theback of the classroom). When facing the front of the classroom, the head-direction cells tell the hippocampus that the head is facing forward.

When the head is turned to face the back of theroom, another set of head-direction cells becomesactive and tells the hippocampus that the head isfacing backward. Yaw motions are sensed by thevestibular system even if the eyes are closed. Theyare not influenced by gravity and can be sensed evenwhen upside-down. Unlike yaw motions, the pitchand roll motions usually have gravity for a reference.This is because the otolith organs that respond togravity are activated along with the semicircularcanals during these motions.Thus, the responses ofthe vestibular system to “pitch” and “roll” will bealtered in microgravity conditions compared tothese responses in Earth’s gravity.

PROCEDURE 1. The roll, pitch and yaw motion diagrams to theright can be emulated by your students outdoorsor in a large area such as a hallway.

2. Demonstrate each of the movements or show thefigures on an over-head chart. Then let all of thestudents attempt each of the different rotations.

3. To begin the rolling cartwheel motion (Figure60), have the students lead with their righthands, with their left ears facing up to the sky.Asthey roll along or rotate in the correct direction,their right ears will face upward, while their leftears are down, and so on.

4. For pitch (Figure 61), have students attempt both a head-over-heelspitch (summersault) and a pitching motion with the arm. Students canalso shake their heads “yes.”

5. For yaw (Figure 62), have students stand and turn left, then right.Students also should try spinning in a pirouette.They can also shake their heads side-to-side as if gesturing “no.”

Figure 62 Diagram of yaw axis motion.

Figure 61 Diagram of body pitching.

Figure 60 Diagram ofrolling motion.


6. Explain to students that the body has different systems to sense yaw,pitch, and roll movements. Introduce the concept of head direction cells, which tell the hippocampus whether the head is facing forward or turned toward the back. Ask them to identify which type of rotationthe head direction cells would be detecting. Mention that the head direction cells are not influenced by gravity, whereas the pitch and roll motions usually have gravity for a reference.

LEARNING ACTIVITY III:Building a Magic Carpet

OVERVIEW Students will compare and contrast pitch androll motions by using a Magic Carpet mazesimilar to one that was used for Neurolabinvestigations.




MATERIALS Each student or team of students will need:

• Scissors• Two strips of cardboard or posterboard

(2.5 inches wide and 18 inches long)• Metal paper fasteners (tang pins)

BACKGROUND The Neurolab Magic Carpet experiment was designed to investigate“pitch” and “roll” in microgravity.The Magic Carpet is a maze shaped likea plus symbol that can work only in a weightless environment.This mazeallowed the astronauts to pitch and roll animals in space, so that withoutmaking any yaw turns, the animals ended up facing the opposite directionfrom where they started.

Spatial Orientation and Visuo-motor Performance Learning Activity III

MAJOR CONCEPTS

• Roll is a sidewaysmotion.

• Pitch is a head-over-heels move-ment.




Neurolab scientists used this trick maze to fool animals into thinking theywere in one place based on their self-motion cues, while their visual sys-tems gave them conflicting information about their locations.The scien-tists wanted to know whether rats’ hippocampi told them they were“home,” or not, by measuring the activity of place cells.

PROCEDURE 1. Tell students they will be creating another puzzle that was used by Neurolab scientists to investigate navigation and spatial orientation in space.

2. Have the students follow the four steps for building a Magic Carpet.

How to Build a Magic Carpet

I. Cut two strips of cardboard 2.5 inches wide and 18 inches long.

II. Put a hole in the center of each strip and fix the two together, perpendicular to one another, with a bent tan pin.Do not split the tangs of the pin when attaching the strips.

III. Hold the tang pin in the hand (palm up), with the head of the tang pin pointing up and the tangs pointing down.

IV. Mark the end of the Magic Carpet that is farthest away fromyou with an “X” to represent an animal, as if the animal were facing you.

3. The Magic Carpet will allow the students to perform the following roll and pitch maneuvers, as shown in Figures 64A and 64B.

4. To perform roll maneuvers, the Magic Carpet should be turned so the head of the tang is pointing down and the student’s hand is on top.Explain to the students that if an animal were on Earth, it would have fallen to the ground. When this experiment is performed in space, the animal will remain on the Magic Carpet, even when it is turned upsidedown, because there is little gravity.

Figure 63 Diagram of construction of a Magic Carpet.


5. To examine pitch maneuvers, have the students turn their wrists and elbows upward so the head of the tang is on top again. Ask them if they see how the “X” is now on the end of the maze closest to them,as if the animal were facing away from them.The students should note that the animal did not have to make any yaw axis motion, yet it endedup facing 180˚ away from where it started (Figures 64C & 64D).

6. Now rotate the Magic Carpet 180˚ in a yaw motion so that the “X” endsup where it started as if the animal were facing you.

EvaluationREVIEW QUESTIONS 1. Which two types of rotation does the Magic Carpet use?

Pitch and roll.

2. How does the brain track movements and position?The hippocampus gets information from many different parts of the brain, and integrates it to assess where the animal is in space.The hip-pocampus uses self-motion cues (vestibular, muscular, body position senses), visual (sight) and auditory (sound) cues.

THINKING 1. If the animal’s brain is not properly encoding pitch and roll motions,CRITICALLY what will its hippocampus tell it about where it is?

If the animal has not moved, except for a 180˚ roll, then the hippocampus will not indicate that the animal has moved, and the hippocampal map should indicate that the animal is in the same place.



64A In hand 64B After roll 64D Starting position64C After roll and pitch

A B C D




2. Will its vestibular system indicate that it has moved at all?The vestibular system should indicate some disturbance, but it cannot give the hippocampus accurate pitch and roll information without gravity.

3. What will its visual cues tell it?No visual cues have been removed, therefore, the animal will receive accurate information regarding its position.

4. What will its place cells do?If the hippocampus has not yet learned how to use this new set of visual cues, then it will rely on the self-motion cues from the vestibularsystem and we think it will tell the animal that it has not moved.

5. What if the animal was turned 180 degrees in the yaw axis(a movement like helicopter blades)? Have the studentsdemonstrate (Figure 65).Since the yaw movements don’t depend on gravity, thevestibular system should accurately inform the hippocampusthat the animal has moved 180˚ and is now facing in theopposite direction.

6. Where does the “X” end up?Where it started.

Note to teacher: If the animal is sensing motion with its vestibular system, itwill not accurately sense that it has motion. It will only detect that it has under-gone a 180 degree “yaw,” and this would indicate that it is 180 degrees fromwhere it started.Vision will indicate that the animal is back where it started. Itis predicted that the animal will think it has rotated 180 degrees because theplace cells are influenced more by the vestibular system than by the inertial navi-gation system.

1.

2.

3.

180˚ Yaw

Figure 65 Diagram of a helicopter blade movement.


Spatial Orientation and Visuo-motor Performance Student Activity Sheet: Learning Activity III

STUDENT ACTIVITY SHEETHow to Build a Magic Carpet

Name ________________________________________________ Date __________________

OBJECTIVE To compare and contrast pitch and roll motions by using a Magic Carpetsimilar to one that was used for Neurolab investigations.

MATERIALS • Scissors• Two strips of cardboard or poster board

(2.5 inches wide and 18 inches long)• Metal paper fasteners (tang pin)

DIRECTIONS You will be creating another puzzle that was used by Neurolab scientiststo investigate navigation and spatial orientation in space. Follow the foursteps to building a Magic Carpet (Figure 66).

PROCEDURES 1. Cut two strips of cardboard 2.5 inches wide and 18 inches long.

2. Put a hole in the center of each strip and fix the two together, perpendicular to one another, with a bent tang pin. Do not split the tangs of the pin when attaching the strips.

3. Hold the tang pin in the hand (palm up),with the head of the tang pin pointing up and the tangs pointing down.

4. Mark the end of the Magic Carpet that is farthest from you with an “X” to represent ananimal, as if the animal were facing you.

Figure 66 Diagram of construction of a Magic Carpet.



Spatial Orientation and Visuo-motor Performance Student Activity Sheet: Learning Activity III

Name ________________________________________________ Date __________________

5. The Magic Carpet will allow you to perform the following roll and pitch maneuvers, as shown above.

6. To perform roll maneuvers, the Magic Carpet should be turned so the head of the tang is pointing down and your hand is on top (Figure 67B).

7. To examine pitch maneuvers, turn your wrists and elbows upward so the head of the tang is on top again (Figure 67C).

Page 2


Figure 67A In hand Figure 67B After roll Figure 67D Starting positionFigure 67C After roll and pitch

A B C D


Spatial Orientation and Visuo-motor Performance Learning Activity IV

LEARNING ACTIVITY IV:Building a 3-D Space Maze: Escher Staircase

OVERVIEW Students will create Escher Staircase modelssimilar to those that were used by the SpatialOrientation Team to investigate the processingof information about pitch, roll, and yaw.




MATERIALS Each student or team of students will need:

• Scissors• Three strips of cardboard or posterboard

(two inches wide and two feet long)• Three metal paper fasteners (tang pins)• Light-weight ball (ping-pong)• Magic marker

BACKGROUND The Neurolab Escher Staircase experiment wasdesigned to investigate whether, within micro-gravity, the hippocampus received inaccurateinformation about pitch and roll motions, butstill had a fully functional yaw motion detection system. On boardNeurolab, investigators used the weightless environment to pit thevestibular and proprioceptive (which is hampered by the microgravityenvironment) against the visual cues of position.

The Escher Staircase is a maze that can be run only in microgravity, becauseit requires movement up and down and sideways along three of the wallsthat make up the inside of the cube.There is no distinction between hori-zontal and lateral movements in a microgravity environment. Rats running

MAJOR CONCEPTS

• Without gravity as areference, the infor-mation provided tothe brain about“pitch” and “roll”motions will be distorted.

• In microgravity,astronauts’ brainswill rely on placecells in the hip-pocampus for information aboutposition.

• Place cells are morestrongly influencedby vestibular andproprioceptive sys-tems visual cues.




the maze in microgravity made three 90˚ pitchesand three 90˚ yaws to end up where they started.The maze is named after the artwork created byM.C. Escher. Escher, an artist, incorporated opticalillusions into his work.

PROCEDURE

1. Discuss the trick maze experiment that the astronauts conducted during the Neurolab mis-sion (this experiment is described in the “Things to Know” section).Tell students that they will be constructing an Escher Staircase similar to the one that was used for the experiment.

2. Have each student or pair of students follow the five steps below to build an Escher Staircase.

How to Build an Escher Staircase

I. Cut cardboard into three strips (A, B and C) that are two inches wide and two feet long.

II. Punch holes near the top and bottom of each strip.

III. Bend the center of each strip to a 90 degree angle.

IV. Use the tang pins to connect strip A to strip B, and strip B to strip C at the holes.

V. Orient the strips at the tang joints so that they are 90 degrees relative to each other, and then connect strip C to strip A.

VI. Draw an arrow on the ping-pong ball.

3. After students have built the Escher Staircase model, have them move the light weight ball along the maze for one full circuit with the arrow pointing in the direction of travel (Figure 68). Have them think aboutwhether it would be possible to walk along the maze in the presence of gravity. What about in space? What types of information would the brain need to remain oriented while walking along the staircase?

Fold

Fold Fold

Tang pin

AA

B

B

C

C

Ping-pong ball

Figure 68 Diagram of a student model of an Escher Staircase.

FoldC

C

FoldB

B

Fold

AA

Figure 69 Diagram of theconstruction of an Escher Staircase.



Evaluation

REVIEW QUESTIONS 1. Describe yaw, pitch, and roll.

Yaw motions are in the horizontal plane relative to your body, for example, shaking your head “no.”

Pitches are turns in the vertical plane, for example, bending over for-ward to touch your toes.

Rolls are turns along the long axis of your body, for example, when you accidentally roll off the bed when you are sleeping.

2. For which of these rotational movements does the brain depend on gravity to process information about the movement?Pitches and rolls.

THINKINGCRITICALLY 1. How many yaw axis turns did the students’ hands make?

Three 90˚ yaw axis turns complete one full circuit on the Escher Staircase.

2. How many pitches? If an animal has no way of encoding the pitch turns, what will the inertial navigation tell the animal’s hippocampus after it has made one full circuit? What will the visual cues tell it?Three 90˚ pitches complete one full circuit on the Escher Staircase.Inertial navigation calculations should tell the animal that it has only made 270˚ worth of turns and it needs to move forward and make onemore 90˚ yaw turn before completing the circuit.Visual cues are accurate. If the animal uses the visual cues quickly, it would accurately indicate that animal’s true position in the environment.

3. Which system will the hippocampus rely on the first time the animal is exposed to the maze, having not yet learned the visual relationships between landmarks?Scientists hypothesize that the animal will rely on selfmotion cues (inertial navigation) at first, because it has not spent enough time in the environment to have learned how the visual cues map out.

4. What about the second day it runs the maze?The animal will have spent enough time looking at the environment tobe able to rely on its placement to tell where it is.

5. Can you make only three 90 degree turns in the yaw axis in space,yet end up right back where you started?Not if you are also moving forward.




6. Without gravity as a reference for sensing the pitch and roll motions,how can you tell if you are back where you started?Using yaw and translational movement cues along, you can keep fairly good track of where you are relative to where you started, only if you have not moved up or down. Without gravity to help your vestibular system keep track of pitches and rolls, if you make translational move-ments after a pitch, your map calculation of your position will be inaccurate.

SKILL BUILDING 1. The artist M.C. Escher created a number of paintings that present gravity-defying optical illusions. Have students find more examples of his work using resources at the library or on the internet.

2. Have students create their own artworks that present paradoxes or illusions in their design.


Spatial Orientation and Visuo-motor Performance Student Activity Sheet: Learning Activity IV

STUDENT ACTIVITY SHEETHow to Build an Escher Staircase

Name ________________________________________________ Date ________________

OBJECTIVE To understand how the brain processes information about pitch, roll, and yaw.

MATERIALS • Scissors• Three strips of cardboard or poster board

(two inches wide and two feet long)• Three metal paper fasteners (tang pins)• Light-weight ball (ping-pong)

DIRECTIONS You will be constructing an Escher Staircase similar to the ones that were used for the experiment. Follow the five steps below to build anEscher Staircase.

PROCEDURES 1. Cut cardboard into three strips (A, B, and C) that are two incheswide and two feet long.

2. Punch holes near the top and bottom of each strip.3. Bend the center of each strip to a 90 degree angle.4. Use the tang pins to connect strip A to strip B, and strip B to

strip C at the holes.5. Orient the strips at the tang joints so that they are 90 degrees

relative to each other, and then connect strip C to strip A.

After you have built the EscherStaircase (Figure 71), move yourhands or a light weight ball along themaze for one full circuit.Think aboutwhether it would be possible to walkalong the maze in the presence ofgravity. What about in space? Whattypes of information would the brainneed to remain oriented while walk-ing along the staircase?

FoldC

C

FoldB

B

Fold

AA

Figure 71 Diagram of an Escher Staircase.

Fold

Fold Fold

Tang pin

AA

B

B

C

C

Ping-pong ballFigure 70 Diagram of construction of an Escher Staircase.


Autonomic Nervous System Regulation


GRADES 5–12

Section IV



Autonomic Nervous System Regulation Introduction

Autonomic Nervous System RegulationTOPIC How did the bodies of Neurolab astronauts function in space?

The autonomic nervous system is the control center of automatic body functions.

INTRODUCTION In the course of daily living, we seldom think about the many processesthat are occurring automatically within our bodies. Fortunately, we don’thave to remember to direct our process of digestion; to maintain ourbody temperature at 37˚celsius; or to control blood pressure and the flowof blood within our circulatory system. All of these processes (and manymore) are governed by a component of the nervous system known as theautonomic nervous system—the body’s automatic control center.

One of the many questions that the Neurolab team asked concerns whathappens to blood pressure regulation in a weightless environment.Thecirculatory system functions to distribute blood throughout the bodyunder conditions created by Earth’s gravity. For example, when you stand,the pull of gravity draws blood away from your head and toward yourfeet. However, you do not faint from lack of oxygen-carrying blood to thebrain. Why not? The answer lies in the body’s ability to regulate bloodpressure. In spite of standing rapidly, the pressure is adjusted in order tomaintain a constant flow of blood to the brain.The level of blood pres-sure—the pressure within your arteries—is determined by the pumping ofblood into the vessels by the heart and the resistance to blood flow bythose blood vessels.Your blood flow to the brain does not change becauseyour autonomic nervous system responds to the challenge of gravity onblood flow by modulating the blood pressure.

This section contains three activities that will help you and your students explore the autonomic nervous system’s regulation of blood pressure.

Things to Know

THE HEART The heart and blood vessels called arteries are responsible for carrying AND BLOOD FLOW oxygen, nutrients, and other substances to all parts of the body. Metabolic

waste products are removed from the tissues by the blood and carried tospecific organs designed to remove them from the body by capillaries andveins. Blood moves through the heart and body because of a very simpleprinciple: blood (or for that matter, any fluid) flows according to pressuredifference—from where pressure is higher to where pressure is lower. The


heart, which acts as a pump, is responsible for creating pressure within theclosed confines of the circulatory system.

Blood pressure within a blood vessel is defined as the force exerted by theblood against the walls of the vessels. Blood pressure within the arteriesrises and falls with the cycles of the heart, or stages by which blood ispumped through the four chambers of the heart and out to the circulation.Blood passes through the heart in a fixed sequence.The heart has fourvalves—the tricuspid, pulmonary, mitral, and aortic—which regulate bloodflow between chambers and between the heart, the pulmonary vessels, andthe systemic vessels (Figure 72). First, blood enters the right atrium fromvery large veins (the superior and inferior vena cavae).The right atriumsqueezes, the tricuspid valve opens, and blood flows to the right ventricle.Next, the right ventricle squeezes, the tricuspid valve closes, the pulmonaryvalve opens, and blood is injected into the pulmonary artery. Blood thentravels through the lungs, where it takes on oxygen and discharges carbondioxide, and enters the left atrium through the pulmonary veins.The leftatrium squeezes, the mitral valve opens, and blood flows into the left ven-tricle. Finally, the very muscular left ventricle squeezes, the mitral valve clos-es, the aortic valve opens, and blood is ejected into the aorta, the largestartery of the body. From there, the oxygen-rich blood is carried to otherparts of the body by a branching system of vessels.

The walls of the blood vessels contain concentric layers of smooth muscle.These muscles and the muscles of the heart are controlled by autonomicnervous system nerves that regulate blood vessel size. A decrease in the

diameters of the blood vessels makes itmore difficult for blood to flow throughthe vessels.When this decrease in sizeoccurs, greater pressure is required toforce the blood through the vessels.Thisincreased pressure is exerted by the heartas it forces blood into the aorta. In con-trast, when the smooth muscles of theblood vessels relax, increasing the diam-eters of the vessels, resistance to bloodflow is reduced and less blood pressureis required to maintain a given flow rate.Not only does the autonomic nervoussystem control the diameter of bloodvessels, it also modulates the rate atwhich the heart pumps—either byspeeding it up, or slowing it down.Through these functions, the autonomicnervous system regulates blood pressure.Figure 72 Diagram of the heart and course of Adapted by permission–Ron White

blood flow through the heart chambers.





REGULATION OF The challenge of maintaining constant blood flow to the brain and other BLOOD PRESSURE tissues while subjected to the effects of Earth’s gravity is met by theBY THE NERVOUS regulation of blood pressure by the autonomic nervous system.The brainSYSTEM receives continuous information regarding the pressure exerted by the

blood on the wall of the larger arteries. This is accomplished by pressuresensors (baroreceptors) strategically located in the wall of these vessels,especially one of the major arteries to the brain (internal carotid artery).These sensors transmit pressure information through nerves to the brain-stem where the autonomic nervous system (Figure 73) monitors thisinformation and reflexively makes the appropriate adjustment of theblood pressure. For example, if the blood pressure momentarily fallsbelow a given set point, the autonomic nervous system increases theresistance to blood flow by reducing the diameter of various arterieswithin the body and increases the rate and force of contraction of theheart, which together result in an appropriate increase in blood pressure.

Figure 73 Diagram of the Autonomic Nervous System.

PARASYMPATHETIC DIVISIONSYMPATHETIC DIVISION

Slows heartbeatStimulatesdigestion

Constrictsairways

Stimulatessalivation

Stimulates pupilDilatespupil

Inhibitssalivation

Constrictsblood vessels

Relaxesairways

Acceleratesheartbeat

Stimulates secretionby sweat glands

Inhibitsdigestion

Stomach

Gall bladder

Pancreas

Liver

Stimulates gallbladder torelease bile

Dilates blood vesselsin intestines and rectum

Stimulates urinarybladder tocontract

Stimulates penile erectionStimulates ejaculation

Inferiormesentericganglion

Stimulatessecretion of epinephrine andnorepinephrine

Relaxes urinarybladder

Stimulatesglucoseproductionand release

Cranial

Cervical

Thoracic

Lumbar

Sacral

Cranial

Cervical

Thoracic

Lumbar

Sacral

Celiacganglion


Autonomic Nervous System Regulation Learning Activity I

The Neurolab Autonomic Team investigated the adaptive changes in theregulation of blood pressure in the microgravity environment of space.They were particularly interested in understanding more about why someastronauts faint from low blood pressure when they try to stand upontheir return to Earth from space missions. Focus has been directed on pos-sible changes in the sensitivity of the pressure sensors and possible changesin the autonomic nervous system in its ability to effectively coordinatechanges in arterial resistance and heart rate in the appropriate modulationof blood pressure, after exposure to microgravity for extended periods.

LEARNING ACTIVITY I:Measuring Blood Pressure in Space

OVERVIEW Students will learn how to measure heart rate and blood pressure accurately and to obtainconsistent measurements during repeated tests.

SCIENCE & Observing, communicating, collecting MATHEMATICS quantitative data, creating charts and graphs,SKILLS drawing conclusions



MATERIALS Each group of students will need:

• Watch or access to clock with a second hand• Stethoscope*• Sphygmomanometer*• Alcohol wipes to clean stethoscope ear plugs

after each use• Copy of student activity sheets: “Determining

Pulse Rate Manually,” “Determining Heart Rate with a Stethoscope,” and “Measuring Blood Pressure with a Sphygmomanometer.”

*These may be obtained from the school nurse.

MAJOR CONCEPTS

• The heart suppliesthe energy to moveblood through the system.

• Blood moves fromwhere pressure ishigher to wherepressure is lower.

• Blood pressure isrecorded as sys-tolic (highestpressure in thepulse) and dias-tolic (lowest pres-sure in the pulse).




BACKGROUND This lesson introduces students to two tools—the sphygmomanometerand the stethoscope—that are used to measure blood pressure and heartrate and engages them in measuring blood pressure and heart ratechanges that occur when the body assumes different postures—lying,sitting, and standing.The Neurolab Autonomic Team was interested inobtaining information on the astronauts’ blood pressures in the micro-gravity environment.They used more sophisticated instruments to contin-uously measure blood pressure and heart rate. Blood pressure is generallyobtained by using a sphygmomanometer and a stethoscope. Heart ratecan be obtained by using the stethoscope (Figure 74) to listen to the rateat which the heart beats or by palpating arteries that are close to the sur-face of the body, and counting the pulse beats.

During this activity, students will hear the sounds ofthe blood as it is pumped into the aorta to identifysounds caused by blood turbulence as a result of twosets of valves within the heart that close at slightly dif-ferent times.The first and second heart sounds, whichoccur in close sequence, represent the closing of dif-ferent valves. When using a stethoscope, the doctorwill hear these valves’ closure as “lup dup, lup dup,lup dup.” Heart rate is determined by counting eitherthe “lups” or “dups.” Usually it is easier to count thelatter during the relatively long pause. (This is thediastole or resting period that occurs between the sec-ond and first heart sounds.)

Students also will learn to find their pulse points andto take (or count) their pulse beats. Palpating pulse

occurs as a result of the expansion of an artery from the blood pushedout by the contraction of the left ventricle. Expansion of an artery, orpulse, can be felt in the neck, at the front of the elbow, behind the knee,and in the foot. Most physicians and nurses palpate the radial artery pulse.It can be felt in the forearm, on the thumb side, where the forearm meetsthe palm.

Heart rate, or the speed at which the heart is beating, can be measured inseveral ways.The simplest method is to record the electrical activity of theheart with an electrocardiogram. However, counting heartbeats heardthrough a stethoscope or pulse beats felt in the wrist or neck for a periodof time are other ways to determine heart rate.

Figure 74 Diagram of student measuringheart rate with stethoscope.


Determining Pulse Rate Manually

PROCEDURE Note to Teacher:You may want to invite a nurse to assist younger students in identifyingheart rate by counting the number of pulse beats. Divide the class into teams of three. One stu-dent will be the subject, one will count the pulse beats, and one will record the results.

1. Have the student counting the pulse beats place the tip of his/her indexand middle fingers on the radius (the bone on the thumb side of the human forearm), and then gradually move the fingertips toward the center of the subject’s wrist (Figure 75).

2. Tell the student not to begin counting the pulse beats until the subject is stationary.The student can begin counting the subject’s pulse beats when the second hand of the watch is on 12. (Have the student do thisfor 30 seconds and he/she should record his/her answers.)

3. Have the student count the number of pulsebeats felt during 30 seconds and record onchart (Figure 76).

4. Each pair of students should take at least three measurements of each other’s pulse rate. Have students record the results.You also may want each student to calculate his/her average pulse rate. Record the average pulse rate of all the students on a class chart on the board.

5. Have the student repeat procedures three andfour with the same subject and record the number of pulse beats in 30 seconds.

6. Ask the students whether, based on the results shown on their individual charts, the subjects of each of the tests were in a steady state.Why or why not?


Figure 75 Photograph of a manual pulse rate count.

Student Name Pulse Rate

Figure 76 Chart for recording pulse rate.

Pulse Rate Data



STUDENT ACTIVITY SHEETDetermining Pulse Rate Manually

Name ________________________________________________ Date __________________

OBJECTIVE To learn how to measure heart rate accurately by counting pulses and toobtain consistent measurements during repeated tests.

MATERIALS • Watch or access to clock with second hand.• Note pad• Pen or pencil

DIRECTIONS This activity requires a team of three. One student will be the subject. Onestudent will count pulses and one will record the results.

PROCEDURE 1. The student being measured should sit comfortably in a chair with feetflat on the floor.

2. The student selected to take the pulse should place the tip of your index and middle fingerson the radius (the bone on the thumb side of the subject’s forearm) and then gradually move the fingertips toward the center of the sub-ject’s wrist (Figure 77).

3. Do not begin counting the pulse beats until the subject is stationary.You can begin count-ing the subject’s pulse beats when the second hand of the watch is on 12. (Do this for 30 seconds.)

4. Count the number of pulses felt during the 30seconds and multiply the result by two to express the pulse rate as heart beats/minute.Record your answers (Figure 78).

5. Take at least three measurements of each other’s pulses. Record the results.

6. Repeat procedures three and four with thesame subject and record the number of beats.

Autonomic Nervous System Regulation Student Activity Sheet: Learning Activity I

Figure 77 Photograph of a manual pulse rate count.

Student Name Pulse Rate

Figure 78 Chart for recording pulse rate.

Pulse Rate Data



Listening to Heart Sounds with a Stethoscope

PROCEDURE Note to Teacher: This experiment should be done in pairs of students of the same gender.

1. The first task is for students to learn how to use a stethoscope.They should take care to make accurate measurements. Students may work inpairs or groups of four, depending on materials available.

2. Have one student within each group place the stethoscope’s earplugs inhis/her ears. (As the stethoscope hangs down from the student’s ears,the metal tubes should be held slightly in front of the student.)

3. Direct each student with a stethoscope to apply the bell (stethoscopes usually have two heads—a bell and a diaphragm (Figure 79) very

lightly to the chest of another student (preferably male, so that the heart sounds will be louder).The diaphragm, applied firmly, is better for high-pitchedsounds.The stethoscope should be placed to the left of the sternum (or breastbone) of the student who is being tested (Figure 74).

4. As the student listens, he/she should move thestethoscope around on the subject’s chest, to the leftof the sternum. Have students notice the loudness ofthe sounds. In general, sounds will be louder whenthe stethoscope is close to the structure generatingthe sounds (the heart, in this case) than when it isfar away. Make sure that students are able to identifythe two sounds (“lup dup”) typically made by theheart.

5. Have the students take turns with the stethoscope,so that all have a chance to hear and identify heartsounds.

Ear plugs

Bell/diaphragm

Rubber Tube

Metal tubes

Figure 79 Diagram of stethoscope.



Student Name Heart RateBeats Per 30 Secs.

Figure 80 Chart for recording heart rate.

Individual Heart Rate Data

Student 1.

Student 2.


Determining Heart Rate with a Stethoscope

PROCEDURE Note to Teacher: This experiment requires at least three students.The experiment should bedone by two students of the same gender.Another student should be the recorder.

1. Have the student being measured sit comfortably in a chair with feet flat on the floor.

2. Have one student place the stethoscope’s earplugs in his/her ears. (As the stethoscope hangs down, the metal tube parts should be directed slightly ahead).

3. Instruct the student to apply the bell of the stethoscope very lightly to the subject’s chest on the left side of the breastbone.

4. Tell the student to listen to the subject’s heart rates by moving the stethoscope around the subject’s chest. Inform the student that sounds will be louder as you get closer to the heart valves. Have one student record the number of beats in 30 seconds on the chart on the Student Activity Sheet (Figure 80).

5. The student should take at least three measurements.

6. Have the students select another subject of the same gender and repeat procedures two and three.

7. To convert heart rate to beats/minute, students should multiply valuesin Figure 78 by two.



STUDENT ACTIVITY SHEETDetermining Heart Rate with a Stethoscope

Name ________________________________________________ Date __________________

OBJECTIVE To learn how to measure heart rate with a stethoscope.

MATERIALS • Watch or access to a clock with a second hand• Stethoscope• Pen or pencil• Note pad

DIRECTIONS Do the following procedures and record your data on the chart.

PROCEDURE 1. One person from your group should place the stethoscope’s (Figure 81) earplugs in his/her ears. (As the stethoscope hangs down, the metal tube parts should be directed slightly ahead.)

2. This person should then apply the bell very lightly to the cheston the left side of the breastbone of a classmate who is the subject. (Students of the same gender should perform this activity on one another.)

3. The person applying the bell should listen to the classmate’s heart rates by moving the stethoscope around the chest.Sounds will be louder when he/she gets closer to the heart’s valves.

4. Listen to the number of beats while watching the clock.

5. Record the number of beats heard per 30seconds on the chart (Figure 82).

6. Take at least three measurements.

7. Select another student (of the same gender)in the group and repeat procedures two andthree.

Ear plugs

Bell/diaphragm

Rubber Tube

Metal tubes

Figure 81 Diagram of stethoscope.

Student Name Heart Rate Beats Per 30 Sec.


Individual Heart Rate Data

Student 1.

Student 2.




Measuring Blood Pressure with a Sphygmomanometer

PROCEDURE 1. Introduce the students to the sphygmomanometer. Most of them will have had their blood pressure taken at some time at a doctor’s office. Askfor a show of hands of students who have had their blood pressure measured.

2. With a student, demonstrate how to use the stethoscope and sphygmo-manometer together to measure blood pressure.

3. Have the person being measured sit comfortably in a chair with feetflat on the floor.

4. Be sure that the person has not over-exerted himself/herself during thelast thirty minutes, e.g., exercising.

5. Attach blood pressure cuff over the brachial artery.This artery is located inside the arm approximately oneinch above the bend of the arm (Figure 83).

6. Place the earplugs of the stethoscope in the operator’sears.

7. Pump the blood pressure cuff up to approximately 200millimeters of mercury.

8. Place the diaphragm of the stethoscope just abovebend of arm. Slowly release cuff at two millimeters ofmercury per second.

9. Listen carefully for the first two consecutive beats. Thisis your systolic blood pressure reading.

10. Continue to listen carefully until you hear the last ofthe two consecutive beats. This is your diastolic bloodpressure reading.

11. Release the pressure from the cuff.

12. Record your readings (Figure 85).

13. Remove the cuff.

Figure 83 Photograph of measurement of blood pressure.



STUDENT ACTIVITY SHEETMeasuring Blood Pressure with a Sphygmomanometer

Name ________________________________________________ Date __________________

OBJECTIVE To learn how to measure blood pressure with a sphygmomanometer (aninstrument for measuring arterial blood pressure consisting of an inflat-able blood pressure cuff, inflating bulb, a gauge showing the blood pressure, and a stethoscope).

MATERIALS • Watch or access to clock with a second hand• Stethoscope• Sphygmomanometer • Alcohol wipes to clean stethoscope ear plugs

after each use• Pen or pencil• Note pad

DIRECTIONS Do the following procedures and record your data in the table.

PROCEDURE 1. Have the person being measured sit comfortably in a chair with feet flat on the floor.

2. Be sure that the person has not over-exerted himself/her-self during the last thirty minutes, such as by exercising.

3. Attach blood pressure cuff over the brachial artery. Thisartery is located inside the arm (Figure 84).

4. The operator should place the earplugs of the stethoscopein his/her ears; place diaphragm of stethoscope just abovebend of subject’s elbow.

5. Use the inflating bulb to pump the blood pressure cuff upto approximately 200 millimeters of mercury.

6. Slowly release cuff at two millimeters of mercury per second.

Figure 84 Photograph of measurement of blood pressure.




7. Listen carefully for the first two consecutive beats. This is your systolicblood pressure reading.

8. Continue to listen carefully until you hear the last of the two consecu-tive beats. This is your diastolic blood pressure reading.

9. Release the pressure from the cuff.

10. Remove the cuff.

11. Record your readings (Figure 85).

Blood Pressure DataStudent Name

Blood PressureDiastolic Systolic

Figure 85 Chart for recording blood pressure.

Name ________________________________________________ Date __________________

Page 2



SIGNIFICANCE • Blood pressure measures utilizing the stethoscope and sphygmo-OF THE TWO manometer cuff will yield the systolic and diastolic pressures.MEASURESTAKEN • Heart rate can be monitored with a stethoscope placed near the valves

of the heart.

• Taking pulse palpitations by placing the tip of the index and middlefingers on the radius will also yield heart rate.

Pulse = heart rate

Sphygmomanometer and stethoscope = diastolic and systolic pressures

EvaluationAt this point, your students should understand two basic tools necessaryfor studying the heart and circulatory system, the stethoscope and sphyg-momanometer.They should also know how to measure and record indi-vidual heart rates.

REVIEWQUESTIONS 1. What different methods can you use to measure heart rate?

The simplest way to measure heart rate is to count the pulse beats.Pulses can be found wherever an artery is accessible. Most people use theradial pulse, located at the wrist. Heart rate can also be measured from beat-by-beat blood pressure recordings or from the electrocardiogram.

2. What is responsible for the movement we call pulse?The pulse occurs when a sudden rush of blood stretches the artery.Arteries stretch as the left ventricle ejects part (over 55%) of its volumeinto the aorta—the largest artery.

3. Why do we take measurements of both systolic and diastolic to determine blood pressure?To determine the maximum and minimum pressures in the circulatory system.

THINKING 1. Using the class data, have students determine if the heart rate and blood CRITICALLY pressure averages they observed from their classmates are high, low or

average for their age group. Ask students to identify and find resources necessary to make this determination.

SKILL BUILDING 1. Have students use resources at the library or on the Internet to investigate lifestyle habits that may cause high blood pressure(hypertension).

2. Based on their research, have students design a lifestyle for someone who may suffer from hypertension.




CONCLUSION Explain that the astronauts on the Neurolab mission used different meth-ods to study blood pressure.They used a small cuff device on the finger(photoplethysmograph) that actually measures the amount of light pass-ing through the tissues of the fingers at different times (Figure 86). As theheart beats, light transmission through the finger varies with the amountof blood in the finger.The pressure in the cuff is regulated continuouslyto maintain light transmission in the finger at a constant level. Pressure inthe cuff is measured by an electronic pressure gauge, and this measure-ment is used as an accurate index of actual blood pressure.You may wantto make an overhead transparency of the photograph below to show tostudents.

When you believe your students are comfortable with, and have masteredmeasuring blood pressure, the next activity can be assigned as an exten-sion to the previous one. It will allow students to see how the body adaptsto changes of posture and the regulation of blood pressure.

AIR

Figure 86 Diagram of a Photoplethysmograph around a finger.

Bladder

Arteries

Air

Bone Detector

LightEmittingDiode


Autonomic Nervous System Regulation Learning Activity II

LEARNING ACTIVITY II:Changing Body Positions:

How Does the Circulatory System Adjust?

OVERVIEW Students will make and compare measure-ments of heart rate and blood pressure fromthree body positions: sitting, standing, and lying.

SCIENCE & Observing, communicating, collecting quantita-MATHEMATIC tive data, recording data in tables and graphs,SKILLS interpreting data, drawing conclusions


CLASS 30 minutes


• Watch or clock with a second hand• Stethoscope*• Sphygmomanometer* (an instrument for

measuring arterial blood pressure consisting of an inflatable blood pressure cuff, inflating bulb and a gauge showing the blood pressure)

• Alcohol wipes to clean stethoscope ear plugs after each use

• Copies of Activity Sheet: “Changing Body Positions”

• Table or bench long enough for a student to lie down

*These may be obtained from the school nurse.

BACKGROUND This activity goes to the “heart” of one of the body’s fundamental mecha-nisms: regulation of blood pressure. When you stand, blood tends to col-lect in the lowest parts of the body. Such translocation of blood could pre-sent problems if the body did not have a method to counteract it. Forexample, if you do not have adequate blood flow (and thus, oxygen) to

MAJOR CONCEPTS

• When a person isstanding on Earth,his/her brain isabove the heartand gravity ispulling fluidstoward the Earth.

• The brain musthave adequateblood flow.

• On Earth, bloodflows to the brainbecause the pres-sure within thesystem is highenough to forceblood upwardagainst the pull ofgravity.



the brain, you will faint. Fortunately, blood within the circulatory systemflows under pressure that is high enough to counteract the force of gravi-ty and allows blood to reach your brain even when you are standing.

This activity will demonstrate one way in which the body responds to changes in posture.

While conducting the activity, students will measure heart rate and bloodpressure in three different body positions—(1) sitting, (2) standing, and(3) lying (Figure 87). Since students will be spending a short period oftime in each position, they probably will find that heart rate and blood

pressure have not reached a steady statewhen they make their measurements.Students should document thesechanges during the time spent in eachof the positions. Measurements madeevery two minutes will allow studentsto observe some of the effects ofchanges of body positions.

As discussed in the previous lessonsand activities, scientists on theAutonomic Team used tools that allowfor much more precise measurementsof blood pressure and heart rate. Afterthis activity, students should have a

very good idea about how the body adapts to changes of posture, basedon their own experimental data.

PROCEDURE 1. Have students conduct this activity in groups of four. One student in each group should serve as the subject, one should measure heart rate (measured as number of pulse beats felt in one minute), one should measure the blood pressure from the other arm, and the other should record measurements as they are called out (Figure 88).

2. Explain to the groups that they will be investigating changes in heart rate and blood pressure that occur when the body moves from sitting to standing to lying. Ask the students to think about and predict changes that might happen. Explain that measurements for each position will takeseven minutes with a maximum of 30 seconds allowed for subject to change positions.

3 1 2

Figure 87 Diagram of three different body positions.



3. Pulse beats should be counted for 30 seconds and blood pressureshould be measured within one minute. Both of these should be mea-sured simultaneously within one minute. For each position, three setsof measurements are made at two-minute intervals. Students makingmeasurements should call out their results to the group recorder, whoshould write the values on the data sheet.

4. Have the groups conduct their experi-ments as follows:

• Subject sits quietly for three minutes.

• Students should take measurements of heart rate and blood pressure simultane-ously for seven minutes.

• After seven minutes, the subject should stand. New measurements should begin as they did in the previous trial.

• After seven minutes, the subject should lie on table. Once again, measurements should begin as they did in the previous trials.

5. After all the data have been collected, the students should convert the 30 second counts of heartbeats into heartbeats per minute by multiplying each of the values by two. Have students create two charts:one of heart rate vs. time and another of blood pressure vs. time.

6. Ask the class to compare the two charts of heart rate and blood pressure. How are the two charts similar? How are they different? What do the results tell us about how the circulatory system adapts to posture changes? Have students think about what might happen to this activity were it conducted under conditions of microgravity.

EvaluationREVIEWQUESTIONS 1. How does blood flow to the brain?

Blood flows to the brain (and every where else in the body) on the basis of pressure. For blood to flow to the brain, the pressure must be lower in the brain than in the arteries that carry blood to the brain.

2. Where does the blood go when the body is in a standing position? In a sitting position?

Measuringheart rate

Countingpulse beats

Figure 88 Diagram of a group taking measurements of blood pressureand counting pulse beats while subject is lying on table.





Blood goes to the lowest part of the body, according to the degree of gravitational pull. Tall people, who have much higher columns of bloodthan short people, are more prone to experience reductions of blood pressure when they stand. Less blood is pooled in the sitting position because the height of the column of blood is less than in the standing position.

3. What happens to blood flow, blood pressure, and heart rate when the body moves from lying to sitting?The heart rate begins to speed; this occurs very rapidly, often within one second. Speeding of the heart helps to prevent a major fall in blood pressure. Also, the vessels constrict to increase resistance to flow and keep blood pressure up.

CRITICAL 1. Challenge your students to think about how the circulatory systemmight respond to changes in a microgravity environment.Which aspectsof the system might stay the same? Which might be different?Absence of gravity causes major changes in the circulation. The mostimportant of these is that there is no gravitational pull of blood towardthe feet when a person stands. Pressure in the feet is the same in lyingand standing positions. Therefore, bloodredistributes from the lower body to theupper body. The autonomic nervous systemdoes not have to adjust to body positions ason Earth. This is not to say that there is noautonomic nervous system control of the cir-culation in space.

2. Ask students to think about why people feelfaint or dizzy (Figure 89A) when they standup very rapidly. Or conversely, why are peo-ple instructed to put their head betweentheir knees (Figure 89B) when they feelfaint?Rapid standing causes a rapid fall of bloodpressure. The fall of pressure reduces bloodflow to the brain momentarily, until the regu-latory mechanisms in the brain and circula-tion can kick in and restore pressure to normal levels. By putting one’s head betweenthe knees, the head becomes dependent,pressure in the arteries of the brain increases,and blood flow to the brain increases.

THINKINGCRITICALLY

Figure 89A Diagram of individual who feels faint.

Figure 89B Diagram of individualwith head between the knees.



Figure 90 Photo of a pressure chamber.

SKILL BUILDING 1. After each group has graphed the sets of measurements they obtained from the experiment, have them produce a written interpretation of the data. Let each group share its write-ups with the class.

APPLICATION Your students should now have a better understanding of how heart rateand blood pressure change in response to body movement.TheAutonomic Team studied similar questions under conditions of micro-gravity.They used different methods, however, to gauge the posturalresponses in space. One of the main issues is that, although astronauts canstand in space, they (and their circulatory systems) do not experience thepull of gravity as they do on Earth.To simulate the gravity environment,the astronauts had the lower halves of their bodies enclosed in a chamberthat was sealed around their waists. Suction was applied to the chamberso that a reduced pressure drew blood to the lower body.The actualchamber that was used is shown in Figure 90.



STUDENT ACTIVITY SHEETChanging Body Positions

Name ________________________________________________ Date __________________

OBJECTIVE To measure the changes of heart rate and blood pressure with changingbody positions.

MATERIALS • A watch or clock • Stethoscope • Alcohol wipeswith a second hand • Pen or pencil • Note pad

• Sphygmomanometer

DIRECTIONS Follow the procedures and record data on the charts (Figures 91 and 92).

PROCEDURE 1. Four students are required to do this activity. (One is the subject, one counts pulses, one measures blood pressure, and one records results.Select the role each person in your group will perform.

2. Have one student from your group sit quietly in a chair with feet flat on the floor.

3. One student should count the number ofpulse beats for 30 seconds, then multiply thatnumber by two and call out the number tothe recorder. (Heart rate is expressed as pulsebeats per minute.)

4. Simultaneously, another student should mea-sure blood pressure within one minute andcall out the number to the recorder.

5. Take three separate measurements at twominute intervals.

6. The recorder should write the numbers calledout on the chart.

7. Repeat procedures “2” – “6” with the studentsubject standing.

8. Repeat procedures “2” – “6” with student subject lying.

9. In order to calculate the heart rate, multiplythe number of pulse beats per 30 seconds bytwo.

Sitting Standing LyingMinutesDiastolic Systolic Diastolic Systolic Diastolic Systolic

Autonomic Nervous System Regulation Student Activity Sheet: Learning Activity II

30

30

30

30

30

30

Beats Beats BeatsMinutes Seconds Sitting Standing Lying

1

2

3

Heart Rate

Blood Pressure

Figure 92 Chart for recording blood pressure.

Minute 1

Minute 2

Minute 3



Autonomic Nervous System Regulation Learning Activity III

LEARNING ACTIVITY III:Baroreceptor Reflex Role Play

OVERVIEW In this activity, the students will learn theimportance of maintaining adequate arterialblood pressure through a role playing exercisewhich demonstrates the baroreceptor reflex(BR) arc—a human model of the BR loop.TheBR arc will demonstrate how the brain process-es information and sends out signals to theheart and arteries.

SCIENCE & Prediction, observing, collecting quantitative MATHEMATICS data and interpreting dataSKILLS



MATERIALS • Index cards to be used as cue cards indicating students’ roles (nine students per group)

BACKGROUND Baroreceptors are specialized neural receptors that sense changes in bloodpressure.The baroreceptor reflex relies on sensing pressure changes in theaorta and carotid artery. If stimulation of the baroreceptors is altered,such as in a microgravity environment, a change would occur in the fir-ing frequency of the nerves connected to the baroreceptors that send sig-nals to the brain.

The baroreceptor reflex circuit includes both sympathetic and parasym-pathetic nerves to the arteries and heart in order to maintain proper arterial blood pressure.The baroreceptor reflex can either increase ordecrease arterial blood pressure in order to return it to normal levels. Ifthe arterial blood pressure increases, the firing rate of the baroreceptorsincreases, sending a greater frequency of impulses through the afferent(inflowing, i.e., towards the brain) baroreceptor nerves.The reflex in thisinstance will cause activation of the vagus nerve, decreasing the rate ofheart contraction to reduce arterial pressure. If the pressure falls, decreased

MAJOR CONCEPTS

• If development inmicrogravity altersthe developmentof the baroreceptorafferent neurons,the circuit may notfunction normallyon Earth.

• The functions ofeach part of thebaroreceptor reflexare required toproperly maintainarterial blood pressure.




firing and frequency of impulse result. In turn, the sympathetic nerves areactivated, thereby causing the heart to contract more rapidly and of bloodvessels to constrict, which will increase arterial blood pressure.

Through this reflex circuit, arterial blood pressure is maintained. It iscrucial to maintain blood pressure within this specified range because theorgan functions of the body depend upon an adequate supply of blood ata relatively constant pressure.

PROCEDURE This activity requires nine students per group.

1. Students should be arranged in groups of nine to represent the parts of the baroreceptor reflex loop according to the diagram in Figure 94.

2. Explain the role of each student so that the students will have a clear understanding of their roles before the activity begins (Figure 93).

3. Tell the student playing the arterial pressure (student #1) to squeeze the arm of the baroreceptor (student #2) firmly to represent increased pressure. In turn, instruct the baroreceptor (student #2) to use a num-ber system to signal increased or decreased pressure to the baroreceptorafferent (student #3).The number system could be one to signal low pressure, two to signal normal pressure and three to signal increased orhigh pressure.

Position Role Task

1 Arterial pressure Squeeze the arm of student #2

2 Baroreceptor Assign the numeric value according to pressure to student #3

3 Baroreceptor afferent Relay the numeric value to student #4 or #5

4 Vasomotor center If the number is low (low pressure), student #4 becomes activated

5 Vagal center If the number is high (high pressure), student #5 becomes activated

6 Vagus nerve Receive information from student #5 and tell student #8 (heart) to decrease rate of pumping

7 Sympathetic nerves Receive information from student #4 and tell student #8 (heart) to increase rate of pumping and tell student #9 (arteries) to constrict to increase pressure

8 Heart Tell student #1 what to do

9 Arteries Tell student #1 what to do, then student #1 tell student #2 what to do

Figure 93 Chart of students’ positions, roles and tasks representing the baroreceptor reflex loop.



Figure 94 Diagram of a baroreceptor reflex loop involved in maintaining proper blood pressure.

4. Direct the baroreceptor (student #2) to report these numbers to the two areas of the medulla—the vasomotor center (student #4) and vagal center (student #5).

EXPLANATION Note to the teacher: At this point, use procedures 5 through 8 to help the students under-stand how the baroreceptor reflex loop works.

5. Once the baroreceptor signals high pressure, the vagal center will tell the vagus nerve to go into action.

6. The vagus nerve goes to the heart and tells it to stop pumping quite so hard and fast. The heart will tell arterial pressure to relax the grip on the baroreceptor’s arm to reduce the number reported by the barore-ceptor to two, normal pressure.

7. If the baroreceptor signals number one (low pressure), the vasomotor center tells the sympathetic nerves to go into action.

8. The sympathetic nerves tell the heart to increase its pumping rate and the arteries to constrict. The arteries and the heart tell the arterial pressure to increase the grip to two, normal pressure. In this case,the baroreceptor would signal normal pressure.

Once pressure is back to normal, you can introduce certain things thatwould change the pressure. For instance, you could say that a lion wasjust spotted and the heart should automatically tell pressure that itincreased its pumping, the vessels should tell pressure that they constrict-ed and the pressure should go to number three (high pressure).

Number correlates to the position (see procedure).




Evaluation

REVIEW 1. What two things are primarily responsible for making arterial bloodQUESTIONS pressure increase or decrease?

The rate at which the blood is pumped into the arteries by the heart and the resistance to blood flow within the arteries are primarily responsible for changes in arterial blood pressure.

2. What areas of the brain are involved with the baroreceptor reflex?The areas of the brain that are involved in the baroreceptor reflex is thevasomotor center and vagal center.

3. What part of the loop might microgravity influence through its presence during human development?Any part of the baroreceptor reflex loop could be influenced by lack ofgravity during human development. The baroreceptor nerves were studied on Neurolab.

4. Why is blood pressure so important?An appropriate blood pressure is important to maintain blood flow through the blood vessels to the brain and other vital organs.

THINKING Have your students write a brief paragraph and explain why they do CRITICALLY not faint when they stand up. You also can have them explain why they

feel light-headed for a few moments when they stand up quickly.


Sleep and CircadianRhythms


GRADES 5–12

Section V



Sleep and Circadian Rhythms Introduction

Sleep and Circadian RhythmsTOPIC How did the Neurolab astronauts’ sleep patterns change

in microgravity?

Did these changes affect the astronauts’ reaction timesand/or performances?

INTRODUCTION Human sleep occurs in a daily circadian rhythm.The periods spent betweensleep and wakefulness (or rest and activity) are coordinated with the envi-ronmental light/dark cycle. The circadian timing system (CTS) acts as amaster control to ensure that the various physiological “systems” of thebody (including the nervous system, the respiratory system, the cardiovas-cular system, and others) work together in a synchronized and coordinatedfashion. If the CTS is not working properly, an organism’s health and per-formance will be negatively affected.

When astronauts fly in space, there is a sunrise andsunset every 90 minutes (one each orbit). Consideringthat the Space Shuttle is flying at 17,000 miles perhour and that the astronauts need to control theShuttle for landing and maintaining orbit, we canbegin to understand why it is important that astro-nauts remain alert and focused. However, since theastronauts’ circadian timing systems have no normal“days” or “nights” (Figure 95), the astronauts’rhythms must rely on the light schedule of the SpaceShuttle and their internal clocks.

Things To KnowCIRCADIAN TIMING SYSTEM The Circadian Timing System (CTS) contains a “clock” located within the

hypothalamus of the brain.This “clock” helps to synchronize bodily func-tions with the external environment.Through its connections with theretina of the eye, it receives and monitors information about the externallight/dark cycle. Based on this information, the clock organizes an ani-mal’s physiology, biochemistry, and behavior.The CTS ensures that thebody’s internal environment is appropriate for the tasks that the body hasto perform. By coordinating the body’s internal clock with sunrise andsunset, the body synchronizes the daily rhythms that help optimize thebody for daily living.

What time is it?

Figure 95 Diagram illustrating an astronaut’s CTShaving no normal “day” or “night” cycle.


Our circadian clocks tell our bodies when itis time to go to sleep and when it is time towake (Figure 96). For example, in humans,our body temperatures rise before we awak-en, remain high during the day when weare active, and drop as we sleep at night.People whose rhythms are not workingproperly may fall asleep at the wrong time,or may not be able to sleep when theyshould.This can be dangerous, since certainactivities, such as driving, learning inschool, working, or even playing, require usto be alert.

The CTS influences sleep and wakefulnessthrough its connections with various brain-stem nuclei. These nuclei use several neuro-transmitters to determine the degree or

level of sleep or wakefulness (alertness). This is accomplished throughbrainstem projections to the thalamus and cerebral cortex. In turn, theCTS modulates this neuronal circuitry to appropriately adjust the durationsof sleep and wakefulness, as well as the levels of consciousness during the24-hour light/dark cycle.

Experiments in which individuals have been deprived of environmentaltime clues (for example, the light of day) have shown that the body’s dailycycles are driven by the CTS clock. For example, the subjects in theseexperiments continue to eat and sleep on a daily cycle, but the timing ofthat cycle is determined by the internal clock, which is close, but notequal to, the 24-hour day. Without the CTS or daily light/dark cues, indi-viduals would generally wake up and go to sleep later each day. However,the length of time spent in sleep and/or wakefulness would remain rela-tively the same during a typical 24-hour cycle.The importance of properCTS function is illustrated by the fact that conditions such as jet-lag, prob-lems resulting from working night shifts, and some sleep and mental dis-orders are associated with dysfunction of the CTS.

During space missions, astronauts may have disrupted sleep and workschedules.This can produce physical symptoms, such as fatigue and gener-al feelings of discomfort (malaise).This could affect the ability of crews toperform their tasks during a mission.The Neurolab Sleep and CircadianRhythms Team examined nervous system regulation of sleep and wakeful-ness during the mission and examined how alterations in sleep patternsaffected astronauts’ abilities to carry out certain tasks in space.


2400

06001800

1200

Dark

Light

Figure 96 Diagram illustrating the 24-hour light/dark cycle.




The Neurolab experiments examined the physiology of the CircadianTiming System (CTS) and homeostatic control (equilibrium in the bodywith respect to various functions) of animals exposed to space flight. Thisdata was compared to those of animals kept in similar environments onEarth. Some of the animals were exposed to a light-dark cycle and somewere exposed to constant light. The constant light environment did notprovide any time cues to the animals, allowing the scientists to examinethe innate characteristics of these animals’ CTS clocks.

SLEEP ANDRESPIRATION Scientists also believed that astronauts’ sleep patterns and quality of sleep

would be affected by other factors as well. For example, they hypothe-sized that, during sleep, the relationship between respiration and heartrate would change in microgravity.They also believed that, during sleep,there would be less oxygen in the arterial blood.Therefore, the astronautswould awaken more easily.The scientists also tested the hypothesis that,when the astronauts were awake, breathing responses to carbon dioxideand low oxygen (hypoxia) levels were increased in microgravity.Theybelieved this would also disrupt sleep.The scientists expected to find thatin microgravity, the chest and abdomen do not move in synchrony duringsleep, thereby adding to sleep disruption.


Sleep and Circadian Rhythms Learning Activity I

LEARNING ACTIVITY I:The Geophysical Light/Dark Cycle

OVERVIEW Students will discover how the light/darkcycle is dictated by the rotation of Earth. Inaddition, they will examine the annualchanges in the duration of light each day asthe planet orbits the sun.

SCIENCE & Observing, communicating, modeling,MATHEMATICS drawing conclusionsSKILLS

PREPARATION None neededTIME


MATERIALS • Globe• Flashlight• Pencil

BACKGROUND Astronauts do not experience the 24 hour light/dark cycle that is normalfor Earth. Instead, while they are orbiting the planet, they experience sunrise and sunset every 90 minutes.Thus, their Circadian Timing Systems(CTS) cannot use external light cues to reset their internal clocks. In general, body functions that occur rhythmically every 24 hours are called circadian rhythms.The body’s primary biological clock is thesuprachiasmatic nucleus located in the hypothalamus. It regulates many of the body’s internal, or endogenous (produced within the organism), rhythms.

The external light/dark cycle, in other words, the hours of daylight (diurnal cycle) and hours of darkness (nocturnal cycle), is particularlyimportant in maintaining regularity of the CTS.The sleep/wake cycle isparticularly susceptible to becoming disrupted by changes in externallight-dark cues.The sleep/wake cycle is one of the endogenous rhythmsof the body.

MAJOR CONCEPTS

• The light/dark cycleis accelerated forastronauts orbitingEarth.

• Changes in thelight/dark cycle maylead to disruptionsof sleep and otherbodily cycles.




The CTS maintains coordination of the organism by monitoring the environment and resetting an internal clock to match the external envi-ronment. Disruptions in this process can affect alertness and performance.When astronauts fly in space, their CTSs have nothing (no normal “days”or “nights”) by which to set themselves.Thus, the astronauts’ rhythmsmust rely on the light schedule of the Space Shuttle and their internalclocks, which may also be altered by the absence of the force of gravityduring space flight.This activity will help students understand the changesthat occur in the light/dark cycle experienced by astronauts while theyorbit Earth.

PROCEDURE 1. Have students mount a flashlight (Figure 97) so that it is stationary and directed at a globe.

2. Instruct students to rotate the globe slowly from west to east (or left to right) to mimic the daily rotation of Earth.

3. Direct students to change the angle of the tilt ofEarth as it faces the sun.The students shouldobserve how the tilt of Earth’s axis alters wherethe sun shines upon the surface. Have themidentify when a particular part of Earth is expe-riencing “day” and when it is experiencing“night.”

4. Help students visualize the acceleratedlight/dark cycle that occurs during orbit byhaving one student rotate a pencil or otherobject around the globe as it continues to spinon its axis.

5. Discuss the implications of changes in the light/dark cycle for astronauts aboard an orbiting space craft.

EvaluationREVIEW QUESTIONS 1. What causes light/dark cycles on Earth?

The sun and the rotation of Earth.

2. How do these cycles change for astronauts aboard a spacecraft in orbit?The Shuttle orbits once every 90 minutes, which provides a “sunrise”and “sunset” every 90 minutes. (Of course, if the astronauts are not near a window, this is not seen.)

Figure 97 Diagram of the geographical light/dark cycle.



THINKING CRITICALLY 1. Ask students what happens if the Circadian Timing System is not

working properly.The sleep/wake cycle will be interrupted and other functions in the body will no longer be properly coordinated.

2. Ask students to think about what might happen to people whoserhythms are not working properly? How might these problems affect certain types of jobs here on Earth?They might become sleepy at inappropriate times (e.g., on the job);excessive tiredness; decrease in motor performance (e.g., driving,riding a bike, catching a ball), etc.

SKILL BUILDING 1. Have students construct a list oftypes of jobs that might causeproblems with the CircadianTiming System, or that mightwork against the body’s naturalsleep/wake cycles.

2. Have students use the Internet orlibrary resources to learn aboutrecently discovered ways to resetthe body’s internal clock toreduce or eliminate jet lag. Howis this related to problems expe-rienced by astronauts? Figure 98 Diagram of students constructing job lists.



Sleep and Circadian Rhythms Learning Activity II

LEARNING ACTIVITY II:How Quick Are Your Responses?

OVERVIEW In this activity, students will learn what reactiontime is and how it is measured.

SCIENCE & Observing, collecting and recording MATHEMATICS quantitative data, calculating averages,SKILLS drawing conclusions


CLASS TIME 50 minutes for each of two parts


• Ruler• Scissors• Pen or pencil• Meter stick• Note pad

BACKGROUND When the sleep/wake cycle is disrupted, people can become fatigued andmay not perform as well as they usually do in a variety of situations.Thisactivity will allow students to learn about reaction time (the time intervalbetween the presentation of a stimulus and the body’s voluntary reaction tothat stimulus) and how reaction time might be affected by lack of sleep.

A Reaction Time Test will be used as a means of determining the time ittakes to react or respond to a given/presented stimulus. Usually, such testsare performed multiple times to account for the normal range of variationin measurements. In Neurolab, a computerized test determined astro-nauts’ reaction times accurately.The corresponding test to be used onEarth depends on gravity and will not work in the weightless environ-ment of space.

Reaction times can vary even for the same individual, because when sub-jects are tired, reaction times can be longer.This lesson focuses on thenormal range of reaction time, how it is measured, and how it varies withalertness level.

MAJOR CONCEPTS

• Reaction time canvary even for thesame individual.

• When subjects aretired, reaction timecan be slower.



PROCEDURE Part One: Learning to Measure Reaction Times

Have students work in pairs to do the following activity:

1. Before beginning, have each student assess, on a scale of one to ten, how sleepy they are—with “1” being not at all sleepy,“5” being somewhat sleepy and “10” being ready to fall asleep instantly.

2. Within each team, have one student hold a ruler with centi-meters (between the thumb and forefinger) vertically at the 30 cm mark with the 0 mark toward the floor (Figure 99).

3. Instruct the student’s partner to position his/her forefinger and thumb at the 0 cm end of the ruler without touching it,so that he/she will be able to grab the ruler easily by closing his/her finger and thumb together (Figure 99).

4. Tell the partner to observe the ruler carefully and then have the first student release the ruler.

5. Direct the partner to close his/her thumb onto the ruler to stop it assoon as the ruler moves.

6. Have the student mark the place where the partner’s fingers were whenhe/she stopped the ruler. The student should discard the first result if the ruler moved less than five centimeters.

7. Have the students repeat the release/catch process 20 times and record and average the results on a chart (Figure 100).

8. Have the students change places so that all will have an opportunity to do this activity.

9. As a class, plot the average values of each student’s reaction times as a histogram, as shown in Figure 101. Have students think about what really is being measured in the activity, and how distance in centime-ters reflects reaction times.

10. Have students calculate the average value of their reaction times and the average value of their sleepiness scores.To do so, add the values together and divide the sum by the number of values.

11. Ask the students to identify the normal range of reaction times in their class population. Example: If sleepiness score is a “3” and the average reaction time is ___, add 3 + ___ and divide the sum by ___ (number

282726252423

Figure 99 Diagram of the forefinger and thumb position.

Figure 100 Example of chart for recording reaction times.

Release # Result

ReactionTimes

Average

1234567891011121314151617181920




of values.) Discuss reaction time variance and alertness level. Ask the stu-dents about the times when distances less than 5 cm occurred during thetrials. Why was it important to discard these results?

Part Two:The Effects of Being Tired on Reaction Times

This exercise is designed to test the students’ reaction times after they are feeling tired. Have students follow the steps below in order to obtain accurate results.

1. Have each student take a ruler home.

2. Inform students that they will need to ask someone at home to helpthem with this activity, and suggest that the students perform thisactivity on a Friday or Saturday night so as not to disrupt their weeklyroutines.

3. Have students ask their parent(s)/guardian(s) for permission to stay upone or two hours beyond their normal bed time. (Remind the studentsthat their partners also will have to stay up.)

4. Instruct students to perform 20 trials of reaction times tests before theygo to bed. Inform them that they must be feeling tired and ready to goto bed before doing this exercise. (Ask students to evaluate how sleepythey feel using the same scale as in the previous activity.)

Figure 101 Example of histogram of the values of students’ reaction times.

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5. Direct the students to repeat the activity after they have each had agood night’s sleep. (Again, ask them to evaluate how sleepy they feelusing the same scale as in the previous activity.)

6. Have students calculate their average reaction times during each trial(night and morning).

7. Compile another set of class averages and a histogram (Figure 101) asbefore. Have students discuss the results. Have them think about anddiscuss the physical and mental symptoms of being tired and howthese might have affected their reaction times.

Evaluation

Students should now have some understanding of how lack of sleep orfatigue can influence their abilities to respond quickly.

REVIEW QUESTIONS 1. What happens to reaction time when one is sleepy or tired?

Reaction time is slower.

2. What are physical signs of being tired? What are mental signs of being tired?One physical sign of being tired is inaccurate motor coordination.A mental sign of being tired is lack of concentration.

THINKING CRITICALLY 1. Ask the students whether or not the sleepiness scores were greater just

before going to bed or in the morning.

2. Ask the students whether or not reaction times were longer in their tests performed just before going to sleep or in their tests done in the morning at school.

3. Discuss with the students what would happen if one was not allowedto sleep for the whole night, and then performed the reaction time test. (Make sure students understand they should NOT do this!)The reaction time would become slower if there were no sleep during the whole night.

SKILL BUILDING 1. Have students conduct a survey of family and friends by asking themto report their sleepiness scores throughout a 24-hour cycle. Are anygeneral trends obvious among all persons surveyed. When are most people alert? When are most people sleepy? How could this information be used to design job or school schedules?



Sleep and Circadian Rhythms Learning Activity III

LEARNING ACTIVITY III:Measuring Your Breathing Frequency at Rest

OVERVIEW Students will learn to measure their restingbreathing rates.

SCIENCE & Observing, collecting and recording quantita-MATHEMATICS tive data, charting data, drawing conclusionsSKILLS



MATERIALS Each team of students will need:

• Watch or access to a clock with a second hand

• Chair• Pen or pencil• Note pad

BACKGROUND Breathing involves the movement of air in and out of the lungs.This facili-tates the exchange of O2 (oxygen) and CO2 (carbon dioxide) between theblood and the external environment, a process known as respiration. Thelevels of O2 and CO2 are tightly regulated and help to determine the rate ofbreathing frequency. Changes in the control of breathing can lead to alteredlevels of O2 and CO2 in the blood. During space flight, the respiratory pat-terns and motions of the chest and abdominal wall are altered. Neurolabscientists used an array of measurements to correlate the changes in respira-tory patterns and oxygen levels in the blood that occur during sleep andwith sleep disturbances.

The number of breaths taken per minute is referred to as breathing frequen-cy or respiratory rate. In a resting person, the average is around 15 breathsper minute, although there are large variations from person to person.Breathing frequency is usually altered while exercising or doing other activ-ities in order to provide the body’s cells and tissues with a continuous andadequate oxygen supply. The name given to the amount of air that isinhaled or exhaled in a single normal breath is “tidal volume,” becausebreathing occurs cyclically—“in” then “out,” “in” then “out”—rather likethe tides in the ocean.

MAJOR CONCEPTS

• Breathing rate iscontrolled by theinteraction of spe-cial pacemakercells in the brain.

• Breathing frequen-cies are differentfor each person.



Special receptor cells (ventilatory chemoreceptors) near major blood ves-sels and on the ventral surface of the brainstem (medulla oblongata) aredesigned to detect levels of oxygen or carbon dioxide in the blood (oftenreferred to as “blood gases”) and cerebrospinal fluid (CSF), respectively.These receptors utilize neuronal pathways to send messages to other cen-ters in the brain which adjust ventilation according to the levels of bloodgases detected. Scientists now believe that the microgravity environmentin space affects the regulation of ventilation and that this may also affectsleep cycles in space.

Oxygen is essential for many processes within the body, especially cellularrespiration. The air we breathe contains about 21% oxygen and 0.05%carbon dioxide. Carbon dioxide is produced as waste during cellular res-piration and must be released out of the body through the lungs. Exhaledgas normally contains about 5% carbon dioxide. Both oxygen and carbondioxide combine with components of the blood in reversible biochemicalreactions.

Aortic Arch

H2

O2

CO2

Respiratory Control Centers

Stretch Receptors(in lung)

Rib Cage

Diaphragm

Medullary RhythmicityArea (MRA) andPre-Bottzinger Complex(located beneath thenucleus ambiguus)

PonsMedulla

Figure 102 Diagram of the centers in the brain.




Centers in the brain (Figure 102) control breathing rate. Although thereare several respiratory control regions in the nervous system, two mainsites are primarily responsible for regulating breathing and the supply ofoxygen to the lungs as well as the rest of the body. One site is the ventralsurface of the medulla in the brainstem.This site detects only pH or car-bon dioxide levels in the blood.The other main site is the carotid bodies,found in the neck.These sites are sensitive to carbon dioxide, oxygen andpH, although their principle purpose is to detect low blood oxygen levels.These receptors are known as chemoreceptors because they sense andrespond to specific dissolved chemicals in plasma.These ventilatory chemo-receptors send signals to the nervous system whenever blood gases devi-ate from the desired set point (e.g., low oxygen or high carbon dioxide).

PROCEDURE 1. Have students work in pairs. Direct one student of each pair to sit quietly with his/her eyes closed.

2. Instruct the partner to observe the student’s breathing carefully by watching the rise and fall of the chest, counting the number of complete breaths that the student makes over the course of one minute using the watch or clock. Have the partner record the number of breaths per minute.

3. Direct the students to change places with their partners, so all students can find their breathing rate at rest.

4. Have the class plot the values of breathing frequencies as a line chart.It should look something like the dia-gram in Figure 103. Have the students calculate the mean (average) value or breathing frequency for the entire class.

5. To calculate a mean value, add the val-ues together and divide the sum bythe number of values.

6. Discuss the results with the class. Have students identify the range of breath-ing frequencies in the class.

Figure 103 Example of a line chart used to plot values of students’ breathing frequencies.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

0



EvaluationREVIEWQUESTIONS 1. What is breathing rate?

Number of breaths per minute.

2. What regulates breathing rate?A large number of things contribute—the blood levels of CO2, O2,limb motion, e.g., running. The main influence is blood CO2.

THINKING CRITICALLY 1. Is the class mean (average) resting breathing rate close to 15 breaths

per minute? Why do most people have similar resting breathing rates?

2. The results farthest from the mean should be considered. Is this normal? (The answer is probably “yes,” because there is some range inbreathing frequencies in any given population.)

SKILL BUILDING 1. Survey the class about exercise habits and physical activities. Arestudents able to detect any relationship between physical activity andresting breathing rate?

2. Have students use resources on the Internet and in the library toinvestigate the effects of certain respiratory disorders on breathing rateand ventilation in general.



Sleep and Circadian Rhythms Learning Activity IV

LEARNING ACTIVITY IV:How Long Can You Hold Your Breath?

OVERVIEW Students will learn how reduced carbon dioxide levels in the blood lower the need tobreathe by comparing breathing rates beforeand after hyperventilation.

SCIENCE & Observing, collecting and recording MATHEMATICS quantitative data, drawing conclusionsSKILLS




• Pen or pencil• Watch or access to a clock with second hand• Chair• Note pad

BACKGROUND Carbon dioxide, produced from cellular respi-ration, is carried in the blood in three main forms:

1. dissolved as CO2 (5%)2. bicarbonate ions (HCO3) (75%)3. bound to hemoglobin and other blood proteins

(Carbamino compounds) (20%)

Carbon dioxide levels are monitored by cells on the ventral medulla in thebrainstem and by the carotid bodies in the neck, which respond tochanges in CO2 levels and pH levels. Unlike the brainstem, the carotidbodies also respond to plasma O2 levels.

A raising of the arterial blood carbon dioxide levels above normal is calledhypercapnia. Hypercapnia can result from insufficient ventilation to clearcarbon dioxide from the lungs.This might occur with a lung disease thatimpairs carbon dioxide removal from the blood, even when ventilation isadequate. In general, increases in blood carbon dioxide levels lead to

MAJOR CONCEPTS

• The brain acts as acentral collectionagent of informa-tion about breathingfrom carbon dioxidesensors, the oxygensensor, mechanicalsensors of breathingmovements, and thecerebral cortex.

• Amounts of carbondioxide in the bloodaffect breathing.



increases in ventilation. Conversely, hyperventilation (rapid shallowbreathing) may drastically lower carbon dioxide levels in blood and willtrigger a slowdown in ventilation.

Oxygen levels also affect ventilation. Hypoxia results from insufficientfresh air reaching the lungs, the blood, and tissues.

The Neurolab team investigated the changes that space conditions cause inventilation and the regulation of blood gases. Under microgravity condi-tions, changes in cerebral blood flow may affect the chemoreceptors in thebrain. Sleep may be affected because ventilation, or lack of ventilation, is apowerful wakening stimulus. If there are alterations in the control of venti-lation in weightlessness, then these may contribute significantly to thepoor quality of sleep that Shuttle crews sometime experience.

PROCEDURE Note to teacher: encourage the students not to cheat by changing their normal breathing pat-terns before starting this activity. Students with respiratory ailments, such as asthma or aller-gies, should not participate in the breath-holding part of this activity.

1. Have students conduct this activity in pairs: one student will be the “subject,” and the other will be the “observer.” Make sure that theobserver has a pen and a watch with a second hand.

2. Have the subject student sit quietly (no talking or moving) in a chair.

3. Instruct each subject to inhale normally, then tellhim/her to stop breathing and signal the observ-ing student by raising his/her finger.The observer should note the starting time.

4. Each subject should hold his or her breath aslong as he/she possibly can (Figure 104).Telleach student to force himself or herself to con-tinue holding his/her breath even if he/she feelslike he/she has to breathe.

5. Instruct each observer to record how longhis/her subjects held their breaths.

6. Ask the subject to take a short rest, then to breatherapidly and deeply for 30 seconds (this is calledhyperventilation). Immediately after hyperventi-lating and at the end of an expiration (outwardbreath), have each subject hold his/her breath,and signal the observing student as before.

Figure 104 Diagram of student recording howlong student can hold her breath.




7. Again, instruct the subject to hold his/her breath as long as possible.

8. Have the observer record how long the subject held his/her breath.

9. Have the students switch roles, so that each student has an opportunity to do the activity.

10. Have the members of the class compare the breath-holding times with and without prior hyperventilation.

11. Check to see if there is any difference. Hyperventilation reduces the level of carbon dioxide in the lungs by blowing it off. The resultantreduction in blood carbon dioxide lowers the need to breathe.

12. Ask your students if, at the point they thought they really had tobreathe, they could talk themselves out of it, even if only for a fewseconds. (There is a strong voluntary component to ventilation.)

13. Have your students compare the individual results of breathingfrequency from Activity One and breath-holding time for this activity.Is there a correlation? Although it may be hard to see, in general,people with a lower response to inhaled carbon dioxide can hold their breath for a longer period of time than those with a higher response.

14. Ask the students to describe what finally forced them to breathe. (Theanswer is, their brain.) The brain acts as a central collection agent of information from a lot of places—carbon dioxide sensors, the oxygensensor, mechanical receptors that sense the absence of breathing movements, and the cerebral cortex.The complex interaction of all these inputs will finally make the students react by breathing.

EvaluationREVIEW QUESTIONS 1. What limits how long one can hold

his/her breath?Many things—CO2, O2, pulmonary stretch receptors, voluntary control.CO2 is the most important in normal people.

2. Where are carbon dioxide levels detected in the body?They are located on the ventral surface of the medulla—the base of the brain (Figure 105).

Figure 105 Diagram of thelocation of the medulla.

Medulla



3. How can levels of carbon dioxide in the body be changed by breathing patterns?If you breathe less, CO2 increases, if you breathe more, CO2 decreases.Exercise produces more CO2, which means we must breathe more to eliminate it.

THINKING 1. What factors, other than high carbon dioxide, might causeCRITICALLY breathlessness?

Low levels of oxygen, or hypoxia. If you have skied at high altitudes,you may have experienced this.The factors that contribute to increased breathing during exercise are many, complex, and still not completely understood. Nevertheless, we have all experienced the sensation of being short of breath and of breathing more when we exercise.

2. Why might the control of ventilation change in weightlessness?The major reasons are: (1) changes in cerebral blood flow alters the central CO2 response; and (2) changes in carotid chemoreceptor responses in the neck that senses O2. (Evidence suggests reason #2 may be more important in weightlessness.)

3. What effect might the change in the control of ventilation have onsleep in weightlessness?It may alter the “sleep architecture,” which will increase arousals (awakenings) and reduce the quality of sleep.

SKILL BUILDING 1. What represents the fizz inbottled or canned soda (Figure106)? Why can’t we see the bub-bles unless the bottle or can isopened? CO2. Under pressure, the CO2

remains dissolved in the soda liq-uid. The reduction in pressurebrings it out of the solution.

Use resources on the Internet orin the library to learn more aboutthe relationship between pressureand dissolved gases.

Figure 106 Diagram of carbonated soft drinks.



Sleep and Circadian Rhythms Learning Activity V

LEARNING ACTIVITY V:Raising the Level of Carbon Dioxide in Your Blood

OVERVIEW In this activity, students will learn about theeffects of increased carbon dioxide in thebloodstream.

SCIENCE & Observing, collecting and recordingMATHEMATICS quantitative data, drawing conclusionsSKILLS




• Large paper bag• Pen or pencil• Watch or access to a clock with a

second hand• Note pad• Chair

BACKGROUND When carbon dioxide levels increase in arte-rial blood, receptors in the medulla withinthe brainstem trigger an increase in breath-ing frequency. In this activity, blood carbondioxide levels are increased by having stu-dents cover their mouths and noses with apaper bag as they breathe. Within the bagcarbon dioxide levels will increase becauseof the higher concentration of carbon dioxide in exhaled air. Because thecarbon-dioxide rich air is “rebreathed,” it leads to increases in the carbondioxide in arterial blood or hypercapnia.

PROCEDURE 1. Have students work in pairs to conduct this activity.

Note to teacher: Some students may find this exercise uncomfortable. Students with respi-ratory ailments should not participate as subjects).As in previous activity, one student within each pair should be the “subject,” and the other should be the “observer.”

MAJOR CONCEPTS

• Breathing can beinvoluntarily modi-fied by raising thelevel of carbon diox-ide in the blood.

• Increasing the CO2 inthe blood will stimu-late ventilation.

• Unlike some otherrhythms in the body,breathing can readilybe modified by will.One can, given somethought, breathemore slowly and withlarger breaths. If aperson is distracted,however, breathingwill return to his/herpersonal “normal”frequency.



2. Within each team, have the student “subject” sit quietly (no talking or moving). Have the observing student count the number of breathstaken by the subject over each 15-second segment of a two minute total time period and record the results.

3. After two minutes, have each subject place a paper bag over his/hernose and mouth, and continue to breathe in and out, as in the diagramin Figure 107.

4. Tell the subject to try to keep a good seal against the face and nose to ensure that only air from within the bag is breathed. Encourage the subject to relax as much as possible and breathe normally.

5. Direct each observing student to watch the bag and write down the number of breaths taken by the subject every 15 seconds.The observing stu-dent should record the number of breaths for two minutes or until the subject removes the bag (if students feel faint they should remove the bag and breathe normally).

6. After the subject removes the bag, have the observing student ask the subject to rate how breathless he/she feels on a scale of one to ten.(One is “not breathless at all,” five is “moderately breathless” and ten is“as short of breath as one could possibly be.”) The observing studentshould record this data.

7. Have the students exchange places and repeat the activity.

EvaluationREVIEW QUESTIONS 1. What type of breathing response occurs when blood levels of carbon

dioxide occur?Breathing frequency and tidal volume (size of breaths) increase and total ventilation increases.

2. Where are the changes in arterial blood concentrations of carbondioxide detected?On the ventral surface of the medulla in the base of the brain.This is termed a “central” response.

Figure 107 Diagram of student breathing in and out of paper bag.




THINKING 1. Why did breathing frequency increase when the mouth and noseCRITICALLY were covered with the paper bag?

As carbon dioxide began to build up in the bag, this “re-breathing experiment” served to increase the carbon dioxide in the arterial blood.This condition of hypercapnia stimulates the central ventilatory chemoreceptor in the ventral medulla, causing an increased breathing frequency.

2. What happened to the tidal volume over the course of the re-breathing experiment?An increase in both breathing frequency and tidal volume results in a large increase in total ventilation.

3. What might happen to a person if the levels of arterial carbon dioxide increased while they were sleeping?Breathing might increase and they could be awaken.

SKILL BUILDING 1. Have students pool their observations and create a class chart ofbreathing rates.


Section VI

Appendices

Glossary

NASA Resources for Educators

Teacher Reply Card

GRADES 5–12



Appendices Glossary

GlossaryAcetylcholine–The neurotransmitter at motor neuron synapses, in autonomic ganglia and a vari-ety of central synapses; which causes cardiac inhibition, vasodilation, gastrointestinal peristalsis,and other parasympathetic effects.

Afferent–Inflowing; conducting towards a center, denoting certain arteries and veins.

Alpha Receptors–A type of receptor for the neurotransmitter, norepinephrine.

Ampula–A saccular dilation of a canal or duct.

Aorta–Large artery that carries blood from the heart to be distributed by branch arteries through-out the body.

Aortic–Relating to the aorta on the aortic orifice of the left ventricle of the heart.

Aperture–An inlet or entrance.

Artery–A relatively thick walled, muscular, pulsating blood vessel conveying blood in a directionaway from the heart.

Atrium–A chamber or cavity to which are connected several chambers or passageways. Usuallyused to describe a chamber of the heart that receives blood from the veins.

Autonomic–Acting independently of volition; relating to the autonomic nervous system.

Axons–Tail-like branch of a neuron that carries the action potential from the nerve cell body to atarget.

Axonal–Pertaining to an axon.

Baroreceptor–Any sensor of pressure changes. For regulation of blood pressure, importantbaroreceptors are located in the aorta and arotid arteries.

Beta Receptors–A type of receptor for the neurotransmitter, norepinephrine.

Brainstem–The entire unpaired subdivision of the brain, composed of the thombencephalon,mesencephalon, and diecephalon as distinguished from the brain’s only paired subdivision thetelecephalon.

Bifurcation–A forking; a division into two branches.


Appendices Glossary

Cupula–A delicate membrane within the semicircular canals that contains fluid and receptor hair cells.

Carotid Artery–Either of the two main arteries that supply blood to the head.

Catecholamine–Refers to several neurotransmitters, such as epinephrine, norepinephrine andserotonin.

Caudal–Pertaining to the tail.

Cerebellum–Prominent hindbrain structure concerned with motor coordinator, posture, and bal-ance. Composed of a three-layered cortex and deep nuclei.

Cholinergic–Refers to synaptic transmission mediated by the release of acetocholine.

Chordamesoderm–That part of the protoderm of a young embryo which has the potentiality of forming notochord and mesoderm.

Coagulate–To convert a fluid or a substance in solution into a solid or gel.

Coriolis Effect–Occurs when the head is in motion and constantly changing direction.

Cortex–The outer portion of an organ, such as the brain.

Corticospinal–Of or relating to the cerebral cortex and spinal cord; the corticospinal fibers arecolumns of motor fibers that run on either side of the spinal cord and are continuations of thepyramids of the medulla oblongata.

Cytokinesis–Changes occurring in the protoplasm of the cell outside the nucleus during celldivision (mitosis).

Cytology–The study of anatomy, physiology, pathology, and chemistry of the cell.

Dendrite–One of the two types of branching protoplasmic processes of the nerve cells (the otheris the axon).

Diencephalon–That part of the prosencephalon composed of the epithalamus, dorsal thalamus,subthalamus, and hypothalamus.

Distal–Far from the point of attachment of origin. Situated away from the center of the body.

Distend–To enlarge from internal pressure.

Dorsal–Pertaining to the back.



Appendices Glossary

Dorsal Thalamas–The large part of the diencephalon located dorsal to the hypothalamus andexcluding the subthalamus and the medial and lateral geniculate bodies.

Ectodermal Cells–The outer layer of cells in the embryo.

Efferent–Conducting (fluid or a nerve impulse) outward from a given organ or part thereof.

Electrocardiogram–Graphic record of the heart’s integrated action currents obtained with theelectrocardiograph.

Embryo–An organism in the early stages of development.

Embryonic–Of, pertaining to, or in the condition of an embryo.

Epi–Upon, following, or subsequent to.

Epinephrine–A catecholamine that is the chief neurohormone of the adrenal medulla.

Epithalamus–A small dorsomedial area of the thalamus corresponding to the hadenula and itsassociated structures.

Escher, M.C. (June 17, 1898 – March 27, 1972)–Native graphic artist of The Netherlands whodesigned the Escher Staircase.

Exteroceptors–One of the peripheral end organs of the afferent nerves in the skin or mucousmembrane, which respond to stimulation by external agents.

Extracellular–Outside the cells.

Fascicle–A band or bundle of fibers, usually of muscles or nerve fibers.

Fiber–A strand of nerve tissue, especially axons or dendrites.

Folia–Plural of folium; a broad, thin, leaflike structure.

Frontal Lobe–The portion of each cerebral hemisphere, anterior to the central sulcus.

Gametocytes–A cell capable of dividing to produce gametes.

Gametes–One of two haploid cells undergoing karyogamy.

Ganglion–An aggregation of nerve cell bodies located in the peripheral nervous system.


Appendices Glossary

Glossopharyngeal–Relating to the tongue and the pharynx.

Gradients–Change of temperature, pressure or other variable as a function of distance, time, etc.

Gyric–Plural of gyrus; one of the prominent rounded elevations that form the cerebral hemi-spheres.

Hippocampus–The complex internally convoluted structure that forms the medial margin (hem)of the cortical mantle of the cerebral hemisphere.

Hypertension–High blood pressure.

Hypo–Prefix denoting deficient, below normal.

Hypothalamus–The ventral and medial region of the diencephalon forming the walls of the ven-tral half of the third ventricle.

Inertial–The tendency of a physical body to oppose any force tending to move it from a positionof rest or to change its uniform motion.

Inhibition–Depression or arrest of a function.

Innervation–The supply of nerve fibers functionally connected with a part.

Karyogamy–Fusion of the nuclei of two cells, as occurs in fertilization or true conjugation.

Lateral–On the side farther from the median.

Lumen–Space in the interior of a tubular structure, such as an artery of the intestine.

Medulla–The caudal (hind) portion of the brainstem.

Medial–Relating to the middle or center.

Meiosis–A special process of cell division comprising two nuclear divisions in rapid successionthat result in four gametocytes, each containing half the number of chromosomes found insomatic cells.

Meninges–One of the membranous coverings of the brain and spinal cord.

Mesencephalon–That part of the brain stem developing from the middle of the three primarycerebral vesicles of the embryo.

Metencephalon–The anterior of the two major subdivisions of the rhombencephalon.



Appendices Glossary

Microtubule–Any of the minute cylindrical structures in cells distributed in the protoplasm andmade up of protein subunits.

Migration–Passing from one part to another.

Mitosis–Cell division that results in nuclei having the same number of chromosomes as the par-ent nucleus; the usual process of cell division with non-reproductive tissues.

Mitotic–Relating to or marked by mitosis.

Mitral–Relating to the mitral or bicuspid valve of the heart.

Myelencephalon–The brain.

Myelinated–Refers to an axon that is ensheathed in the fatty, insulating substance, myelin.

Neonatal–Relating to the period immediately succeeding birth and continuing through the first28 days of life.

Nerves–A whitish cordlike structure composed on one or more bundles of myelinated orunmyelinated nerve fibers, or more often mixtures of both, coursing outside of the central ner-vous system, together with connective tissue within the fascicle and around the neurolemma ofindividual nerve fibers.

Neural–Relating to any structure composed of nerve cells or their processes, or that on furtherdevelopment will evolve into nerve cells.

Neurolemma–A cell that enfolds one or more axons of the peripheral nervous system.

Neurons–Nervous system cell consisting of the nerve cell body, dendrites and axon.

Neurotransmitter–Any specific chemical agent released by a presynaptic cell, upon excitation,that crosses the synapse (gap between cells) to stimulate or inhibit the postsynaptic cell.

Neurula–Stage in embryonic development after the gastrula state, in which the prominentprocesses are the formation of the neural plate and the plate’s closure to form the neural tube.

Neurulation–Processes involved in the formation of the neurula stage.

Norepinephrine–A neurotransmitter found in the brain and sympathetic nervous system.

Nucleus–In cytology, typically a rounded or oval mass of protoplasm within the cytoplasm of aplant or animal cell, in which the chromosomes are located.


Appendices Glossary

Occipital Lobe–The posterior, somewhat pyramid-shaped, part of each cerebral hemisphere.

Olfactory–Relating to the sense of smell.

Optics–The science concerned with the properties of light, its refraction and absorption, and therefracting media of the eye in that relation.

Organs–Any part of the body exercising a specific function as of respiration, secretion, digestion.

Organogenesis–Formation of organs during development.

Otolith–Crystalline particles of calcium carbonated and a protein adhering to the gelatinousmembrane of the maculae of the utricle and saccule.

Oxygenation–Addition of oxygen to any chemical or physical system.

Palpating–Examination with the hands, for example, when feeling the heart or pulse beat.

Parasympathetic–Pertaining to the division of the autonomic nervous system that organizes thebody’s responses that save energy and balance the body’s various systems.

Parietal–Relating to the wall of any cavity.

Peripheral–Relating to or situated at the periphery (or edge) of something or extremeties; theouter part or surface.

Periphery–The part of a body away from the center.

Peristalsis–The movement of the intestine or other tubular structure, caused by successive wavesof involuntary muscular contractions.

Pharynx–The upper expanded portion of the digestive tube, between the esophagus below andthe mouth and nasal cavities above and in front.

Pitch–An up and down movement.

Plasma–The fluid portion of the circulating blood.

Postnatal–Occurring after birth.

Postganglionic–Relating to or being an axon originating from a cell body within an autonomicganglion.

Postsynaptic–Pertaining to the area of the distal side of a synaptic cleft.



Appendices Glossary

Presynaptic Cell–Pertaining to the area on the proximal side of a synaptic cleft.

Preganglionic–Situated proximal to or preceding a ganglion, referring specifically to the pregan-glionic motor neurons of the autonomic nervous system (located in the spinal cord and brainstem).

Proliferation–Growth and reproduction of similar cells.

Prophase–The first stage of mitosis or meiosis, consisting of linear contraction and increase inthickness of the chromosomes.

Proprioception–The sense or perception, usually at a subconscious level, of the movements andpositions of the body and especially its limbs, independent of vision.

Prosencephalon–The anterior primitive cerebral vesicle and the most rostral of the three primarybrain vesicles of the embryonic neural tube.

Pulmonary–Relating to the lungs, to the pulmonary artery, or to the aperture leading from theright ventricle of the heart into the pulmonary artery.

Proximal–Nearest the trunk or the point of origin said of part of a limb, or an artery or a nerve.

Pyro–Prefix referring to fire, heat or fever.

Radius–The lateral and shorter of the two bones of the forearm.

Receptor–A structural protein molecule on the cell surface or within the cytoplasmthat binds to a specific factor, such as a hormone, antigen, or neurotransmitter.

Replicate–One of several identical processes or observations; to repeat.

Rhombencephalon–That part of the developing brain that is the most caudal (towards the tail)of the three primary vesicles of the embryonic neural tube.

Roll–To cause to revolve by turning over and over on or as if on an axis.

Rostral–Towards the front or head.

Somatic–Relating to the soma or trunk, the wall of the body cavity, or the body in general.

Saccule–One of the otolith organs of the vestibular system.

Spatial–Relating to space or position in three dimensions.

Sternum–A long, flat bone, articulating with the cartilages of the first seven ribs and with theclavicle, that forms the middle part of the anterior wall of the thorax.Breast bone.


Appendices Glossary

Stethoscope–An instrument originally devised by Laennec for aid in hearing the respiratory andcardiac sounds in the chest, but now modified in various ways and used to listen to vascular orother sounds anywhere in the body.

Stress–Reactions of the body to forces of a deleterious nature, infectious, and various abnormalphysiologic equilibrium.

Sub–Prefix, denoting beneath, less than the normal, inferior.

Subcortical–Beneath the cerebral cortex.

Sulcus–One of the grooves or furrows on the surface of the brain, bounding the several convol-untions or gyri.

Sympathetic Ganglia–Those ganglia of the autonomic nervous system that receiveefferent fibers originating from preganglionic visceral motor neurons in the intermediolateral cellcolumn of thoratic and upper lumba spinal segments.

Sympathetic–Part of the autonomic nervous system of vertebrates that organizes and regulatesthe body’s response to stress.

Synapse–The functional membrane-to-membrane contact of the nerve cell with a target cell(another nerve cell or other type of cell).

Synthesis–A building up, putting together, composition stage in the cell cycle; production of amolecule through chemical processes.

Tectum–Any rooflike covering or structure.

Telencephalon–The anterior division of the prosencephalon, which develops into the olfactorylobes, the cortex of the cerebral hemispheres, and the subcortical telencephalic nuclei, and thebasal ganglia.

Temporal Lobe–The lowest of the major subdivisions of the cortical mantle, forming the posteri-or two-thirds of the ventral surface of the cerebral hemisphere.

Thalamus–The large ovoid (an oval egg-shaped form) mass of gray matter that forms the largerdorsal subdivision of the diencephalon.

Tricuspid–Having three points, prongs, or cups. As the tricuspid valve of the heart.

Ulna–The medial and larger of the two bones of the forearm.

Utricle–The larger of the two membranous sacs in the vestibles of the labyrinth, lying in theelliptical recess.



Appendices Glossary

Vagal–Relating to the vagus nerve.

Vagus Nerve–The nerve responsible for slowing heart rate; part of the parasympathetic nerve system.

Vasoconstriction–Narrowing of the blood vessels.

Vasodilation–Widening of the lumen of blood vessels.

Vasomotor–Causing constriction of the blood vessels.

Vein–A blood vessel carrying blood toward the heart; all the veins except the pulmonary carrydark or oxygenated blood.

Ventricle–The thick-walled chambers of your heart that pump blood into your lungs and body.

Ventro–The belly.

Ventrolateral–Both ventral and lateral.

Vestibulo-Ocular Reflex (VOR)–A reflex that allows your eye to remain fixed on an objectalthough your head or the object is moving.

Vestibular–Relating to the sense of balance.

Yaw–A side-to-side movement.


Appendices Resources

NASA Resources for Educators

NASA’s Central Operation of Resources for Educators

NASA’s Central Operation of Resources for Educators (CORE) was established for the national andinternational distribution of NASA-produced educational materials in audiovisual format.Educators can obtain a catalogue and an order form by one of the following methods:

• NASA CORELorain County Joint Vocational School15181 Route 58 SouthOberlin, OH 44074

• Phone: (440) 774-1051, Ext. 249 or 293• Fax: (440) 774-2144• E-mail: [email protected]• Home Page:http://spacelink.nasa.gov/CORE

Educator Resource Center Network

To make additional information available to the education community, the NASA EducationDivision has created the NASA Educator Resource Center (ERC) network. ERCs contain a wealth ofinformation for educators: publications, reference books, slide sets, audio cassettes, videotapes,telelecture programs, computer programs, lesson plans, and teacher guides with activities.Educators may preview, copy, or receive NASA materials at these sites. Because each NASA FieldCenter has its own areas of expertise, no two ERCs are exactly alike. Phone calls are welcome ifyou are unable to visit the ERC that serves your geographic area. A list of the centers and theregions they serve includes:

AK, AZ, CA, HI, ID, MT, NV, OR,UT, WA, WYNASA Educator Resource CenterMail Stop 253-2NASA Ames Research CenterMoffett Field, CA 94035-1000Phone: (650) 604-3574

CT, DE, DC, ME, MD, MA, NH,NJ, NY, PA, RI,VTNASA Educator Resource LaboratoryMail Code 130.3NASA Goddard Space Flight CenterGreenbelt, MD 20771-0001Phone: (301) 286-8570

CO, KS, NE, NM, ND, OK, SD,TXJSC Educator Resource CenterSpace Center HoustonNASA Johnson Space Center1601 NASA Road OneHouston,TX 77058-3696Phone: (281) 483-8696

FL, GA, PR,VINASA Educator Resource LaboratoryMail Code ERLNASA Kennedy Space CenterKennedy Space Center, FL 32899-0001Phone: (407) 867-4090




KY, NC, SC,VA, WVVirginia Air and Space MuseumNASA Educator Resource Center forNASA Langley Research Center600 Settler's Landing RoadHampton,VA 23669-4033Phone: (757) 727-0900 x 757

IL, IN, MI, MN, OH, WINASA Educator Resource CenterMail Stop 8-1NASA Lewis Research Center21000 Brookpark RoadCleveland, OH 44135-3191Phone: (216) 433-2017AL, AR, IA, LA, MO,TNU.S. Space and Rocket CenterNASA Educator Resource Center for NASA Marshall Space Flight CenterP.O. Box 070015Huntsville, AL 35807-7015Phone: (256) 544-5812

MSNASA Educator Resource CenterBuilding 1200NASA John C. Stennis Space CenterStennis Space Center, MS 39529-6000Phone: (228) 688-3338

NASA Educator Resource CenterJPL Educational OutreachMail Stop 601-107NASA Jet Propulsion Laboratory4800 Oak Grove DrivePasadena, CA 91109-8099Phone: (818) 354-6916

CA Cities Near the CenterNASA Educator Resource Center forNASA Dryden Flight Research Center45108 N. 3rd Street EastLancaster, CA 93535Phone: (805) 948-7347

VA and MD's Eastern ShoresNASA Educator Resource LabEducation Complex

Visitor Center Building J-1NASA Wallops Flight FacilityWallops Island,VA 23337-5099Phone: (757) 824-2297/2298

Regional Educator Resource Centers

Regional Educator Resource Centers offer more educators access to NASA educational materials.NASA has formed partnerships with universities, museums, and other educational institutions toserve as RERCs in many states. A complete list of RERCs is available through CORE, or electroni-cally via NASA Spacelink at http://spacelink.nasa.gov

NASA On-line Resources for Educators

NASA On-line Resources for Educators provide current educational information and instructionalresource materials to teachers, faculty, and students. A wide range of information is available,including science, mathematics, engineering, and technology education lesson plans, historicalinformation related to the aeronautics and space program, current status reports on NASA pro-jects, news releases, information on NASA educational programs, useful software and graphics



files. Educators and students can also use NASA resources as learning tools to explore the Internet,accessing information about educational grants, interacting with other schools which are alreadyon-line, and participating in on-line interactive projects, communicating with NASA scientists,engineers, and other team members to experience the excitement of real NASA projects.

Access these resources through the NASA Education Home Page:http://www.hq.nasa.gov/education

NASA Television

NASA Television (NTV) is the Agency's distribution system for live and taped programs. It offersthe public a front-row seat for launches and missions, as well as informational and educationalprogramming, historical documentaries, and updates on the latest developments in aeronauticsand space science. NTV is transmitted on the GE-2 satellite,Transponder 9C at 85 degrees Westlongitude, vertical polarization, with a frequency of 3880 megahertz, and audio of 6.8 mega-hertz.

Apart from live mission coverage, regular NASA Television programming includes a Video Filefrom noon to 1:00 pm, a NASA Gallery File from 1:00 to 2:00 pm, and an Education File from2:00 to 3:00 pm (all times Eastern).This sequence is repeated at 3:00 pm, 6:00 pm, and 9:00pm, Monday through Friday. The NTV Education File features programming for teachers and stu-dents on science, mathematics, and technology. NASA Television programming may be video-taped for later use.

For more information on NASA Television, contact:NASA HeadquartersCode P-2NASA TVWashington, DC 20546-0001 Phone: (202) 358-3572 NTV Home Page:http://www.hq.nasa.gov/ntv.html

How to Access Information on NASA’s Education Program, Materials, and Services,EP-1998-03-345-HQ

This brochure serves as a guide to accessing a variety of NASA materials and services for educa-tors. Copies are available through the ERC network, or electronically via NASA Spacelink. NASASpacelink can be accessed at the following address: http://spacelink.nasa.gov

The Brain in Space A Teacher's Guide with Activities for Neuroscience

EDUCATOR REPLY CARDTo achieve America’s goals in Educational Excellence, it is NASA’s mission to developsupplementary instructional materials and curricula in science, mathematics, geogra-phy, and technology. NASA seeks to involve the educational community in thedevelopment and improvement of these materials. Your evaluation and suggestions arevital to continually improving NASA educational materials.

Otherwise, please return the reply card by mail. Thank you.

1. With what grades did you use the educator guide?Number of Teachers/Faculty:

K-4 5-8 9-12 Community College

College/University - Undergraduate Graduate

Number of Students:

K-4 5-8 9-12 Community College

College/University - Undergraduate Graduate

Number of Others:

Administrators/Staff Parents Professional Groups

General Public Civic Groups Other

2. What is your home 5- or 9-digit zip code? __ __ __ __ __ — __ __ __ __

3. This is a valuable educator guide?

❏ Strongly Agree ❏ Agree ❏ Neutral ❏ Disagree ❏ Strongly Disagree

4. I expect to apply what I learned in this educator guide.

❏ Strongly Agree ❏ Agree ❏ Neutral ❏ Disagree ❏ Strongly Disagree

5. What kind of recommendation would you make to someone who asks about this

educator guide?

❏ Excellent ❏ Good ❏ Average ❏ Poor ❏ Very Poor

6. How did you use this educator guide?

❏ Background Information ❏ Critical Thinking Tasks

❏ Demonstrate NASA Materials ❏ Demonstration

❏ Group Discussions ❏ Hands-On Activities

❏ Integration Into Existing Curricula ❏ Interdisciplinary Activity

❏ Lecture ❏ Science and Mathematics

❏ Team Activities Standards Integration

❏ Other: Please specify: _________________________________________

7. Where did you learn about this educator guide?

❏ NASA Educator Resource Center

❏ NASA Central Operation of Resources for Educators (CORE)

❏ Institution/School System

❏ Fellow Educator

❏ Workshop/Conference

❏ Other: Please specify: _________________________________________

8. What features of this educator guide did you find particularly

helpful?

____________________________________________________________

______________________________________________________________

9. How can we make this educator guide more effective for you?

______________________________________________________________

______________________________________________________________

10.Additional comments:

______________________________________________________________

______________________________________________________________

Today’s Date:

Please take a moment to respond to the statements and questions below.You can submit your response through the Internet or by mail. Send yourreply to the following Internet address:

http://ehb2.gsfc.nasa.gov/edcats/educator_guide

You will then be asked to enter your data at the appropriate prompt.

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Neuroscience Teachers Guide

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